Sometimes, we may need to know the table's metadata like
    Column Name,
    Data Type
    Column Size
    Index
    Constraint
    ETC.

And to be honest there are various ways to determine this but in the tip, we are going to share 2 simple ways to determine the table's detail

1. SP_HELP
The syntax of sp_help is very simple as shown below
SP_HELP 'TABLENAME'
GO

For example, if I have a Users table in my database then I can write the SQL command like below and hit F5
SP_HELP 'Users'
GO

Now, the other way is very very simple. In this, you don't have to write SP_HELP

Just write the tableName in the Query window. Select the table Name and hit ALT + F1

This will show exact same result which you get from SP_HELP.

I hope this simple tip might help you.

Thanks

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This is an interesting query in every developer's mind: What happens if the table has columns with default values only and we want to insert a new row with a default value?

Isn't it interesting? I am pretty much sure your mind horses started running and you are trying to solve this query but if not then never mind below few steps will help you to understand this concept.

To understand this let's take an example. Let's create a table with the default value  (Just to let you know we are using SQL Server :) )
CREATE TABLE #CSharpRegistration (Id INT IDENTITY(1,1),
FirstName VARCHAR(250) DEFAULT 'Registration fname',
LastName VARCHAR(250) DEFAULT 'Registration Lname')

Now, once the table is created you might be wondering what's new in this, it has a default value and identity column. There is nothing much in creating a statement but magic exists in the below statement.
INSERT INTO #CSharpRegistration (FirstName,LastName) VALUES (DEFAULT,DEFAULT)

Once you write the above insert statement and run it. You will find that a default row is inserted in the table. To check run below simple SQL Statement.
SELECT * FROM #CSharpRegistration

See, below image of execution of above statement.

I hope this small article solves your query.

Please, do comment and share if you like it.

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In this article, we will learn how to use Built-In functions in SQL Server.

What are Built-In functions?
A built-in function is a piece for programming that takes zero or more inputs and returns a value. There are many built-in functions in SQL Server. Here we are discussing about string, date, and time functions in SQL Server.

String Functions
ASCII()
ASCII (American Standard Code for Information Interchange) is a code that uses numbers to represent characters. This function returns the ASCII value for the specific character. To get the ASCII code of a character, we can call the ASCII() function. It takes a character as an argument and returns the ASCII code of the character. For example:
SELECT ASCII('A') AS [In ASCII Format]
Result: ‘65’   (ASCII code of “A” is 65)
SELECT ASCII('a') AS [In ASCII Format]
Result: ‘97’   (ASCII code of “A” is 65)

CHAR()
This function returns the character based on the ASCII code. It takes a numeric value as an argument and returns the character. For example:
SELECT CHAR(65) AS [In CAHR Format]
Result: ‘A’   (ASCII code of “A” is 65)
SELECT CHAR(85) AS [In CHAR Format]
Result: ‘U’   (ASCII code of “U” is 85)

CHARINDEX()
This function returns the position of a substring in a string. This function return 0(Zero) if the substring is not found. It takes three arguments. Syntax,
CHARINDEX (substring, string) / CHARINDEX (substring, string, start_position)

In the above syntax “substring” is the string to search for. “string” is the string to be searched. “start_position” is the position where the search will start. This is an optional parameter. If it is zero or negative value, the search starts at the beginning of the string.

SELECT CHARINDEX('CHAR', 'SQL Server CHARINDEX() function examples') AS MatchPosition;
Result: ‘A’   (We get 20 as the index point of “CHAR”)
SELECT CHARINDEX('CHAR1', 'SQL Server CHARINDEX() function examples') AS MatchPosition;
Result: ‘A’   (We get 0 as the index point of “CHAR1”, because it’s not found in the above string)

SOUNDEX()& DIFFERENCE()
This function compares two SOUNDEX values, and returns an integer. The integer value indicates the match for the two SOUNDEX values from 0 to 4, where 0 indicates weak or no similarity and 4 indicates strong similarity.

The SOUNDEX() function converts a string to a four-character code. This function compares the similarity between strings in terms of their sounds when it is spoken.

For example,
SELECT SOUNDEX('Juice') soundex1,SOUNDEX('55') soundex2,DIFFERENCE('Juice', '55');
Result: ‘J200, 0000, 0’   (Here SOUNDEX codes are totally different so we get 0)
SELECT SOUNDEX('Juice') soundex1,SOUNDEX('Debezium') soundex2,DIFFERENCE('Juice', 'Debezium');
Result: ‘J200, D125, 1’   (Here SOUNDEX codes are near to each other so we get 1)
SELECT SOUNDEX('Juice') soundex1,SOUNDEX('Apple') soundex2,DIFFERENCE('Juice', 'Apple');
Result: ‘J200, A140, 2’   (Here SOUNDEX codes are more near to each other so we get 2)
SELECT SOUNDEX('India') soundex1,SOUNDEX('Indian') soundex2,DIFFERENCE('India', 'Indian');
Result: ‘I530, I535, 3’   (Here SOUNDEX codes are near to similar so we get 3)
SELECT SOUNDEX('Juice') soundex1,SOUNDEX('Jucy') soundex2,DIFFERENCE('Juice', 'Jucy');
Result: ‘J200, J200, 4’   (Here SOUNDEX codes are same so we get 4)

FORMAT()
Using this function we can format a value with a specified format. This function can be applied to various types of values such as integers, floating-point numbers, date, or time. It takes three arguments or parameters. Syntax:

FORMAT(value, format, culture)
value: is the type of value to be formatted. It can be a number, a date or time.

format : it specifies the format you want to apply to the first argument.

culture : is optional parameter, specifies a culture.

SELECT FORMAT(9658254870, '###-###-####');
Result: ‘965-825-4870’   (We get the above number in “###-###-####” format)
DECLARE @Salary INT = 56.68;
SELECT @Salary, FORMAT(@Salary, N'F'), FORMAT(@Salary, N'C', N'en-IN');
Result: ‘56, 56.00, ₹ 56.00’
SELECT FORMAT(GETDATE(), 'yyyy-MMM-dd'), FORMAT(GETDATE(), 'dd-MM-yyyy');
Result: ‘2021-Dec-27, 27-12-2021’   (Here we get the same date in two different format)

LEFT()
This function is used to get a number of characters from a string starting from left. This function takes two arguments. The first argument specifies the original string and the second argument specifies the number of characters from the most-left. For example:
SELECT LEFT('Peter Scott', 4) AS [Name];
Result: ‘Peter’   (We get only 4 character of the string)
SELECT LEFT('Sql Server Function Examples', 13) AS [Example];
Result: ‘965 Built-In Functions’

LEN()
This function returns the length of a string. This function takes one argument as the string to be considered. For example:
SELECT LEN('Peter Scott') AS [Count1];
Result: ‘12’   (Returns total character of the string including space)
SELECT LEN('Built-In Functions LEN() in SQL Server – Part One') AS [Count2];
Result: ‘49’   (Returns total character of the string including space)

LOWER() & UPPER()
LOWER() converts a string to lower-case and UPPER() function converts a string to upper-case. These functions take one argument as a string.
SELECT LOWER('Peter Scott') AS [Name];
Result: ‘peter scott’   (Returns the given string in lower case)
SELECT UPPER('Built-In Functions in SQL Server – Part One') AS [Example];
Result: ‘BUILT-IN FUNCTIONS IN SQL SERVER – PART ONE’   (Returns the given string in upper case)

LTRIM() & RTRIM()
LTRIM function removes all leading spaces from a string starting from left and RTRIM() function removes all leading spaces from a string from right.
SELECT LTRIM('       Peter Scott') AS [Name];
Result: ‘Peter Scott’   (Remove all space from left side of the string)
SELECT RTRIM('       Peter Scott         ') AS [Name];
Result: ‘       Peter Scott’   (Remove space from right)
SELECT LTRIM(RTRIM('       Peter Scott         ')) AS [Name];
Result: ‘Peter Scott’   (Remove all space from both left and right side of the string)

PATINDEX()
The PATINDEX() function returns the first occurrence of a pattern in a string. It returns 0 if the pattern is not found. It takes two arguments. First one is the pattern to search and it must be surrounded by “%”. Here we can also use other wildcards like “%”, “_”, “[]”, “[^]”. The second one is the string to be searched.

SELECT PATINDEX('%Part%', 'Built-In Functions in SQL Server – Part One') AS [Example];
Result: ’36’   (we search the pattern %Part% in the specified string)
SELECT PATINDEX('%S_rver%', 'Built-In Functions in SQL Server – Part One') AS [Example];
Result: ‘27’   (we search the position for the pattern “S” followed by “rver” in the string)
SELECT PATINDEX('%[^0-9A-z]%', 'Built-In Functions in SQL Server – Part One') AS [Example];
Result: ‘6’   (Here we want to finds out the position of the character without an alphabet, number)

REPLACE()
This function replaces all occurrences of a substring within a string, with a new substring. This function takes three arguments. The first is the string that will be used as reference. The second argument is a character or a sub-string to look for in the first argument. The third argument is a character or a sub-string to replace the second argument. For example: If we want to replace “SQL Server” as “MS SQL Server” in the “'Built-In Functions in SQL Server – Part One'” string.

SELECT REPLACE('Built-In Functions in SQL Server – Part One', 'SQL Server', 'MS SQL Server') AS [Example];
Result: ‘Built-In Functions in MS SQL Server – Part One’   (Here we replace “SQL Server” with “MS SQL Server”)
SELECT REPLACE('Peter Scott Thomas', 'Scott', '') AS [Name];
Result: ‘Peter Thomas’   (Here we replace “Scott” with “” blank)

REPLICATE()
This function repeats a string with a specified number of times. It takes two arguments. The first argument is the string to repeat and the second argument is no of time to repeat the string. For example:

SELECT REPLICATE(' Built-In Functions in SQL Server', 4) AS [Example];
Result: ‘Built-In Functions in SQL Server Built-In Functions in SQL Server Built-In Functions in SQL Server Built-In Functions in SQL Server’   (Here we get the above string repeated 4 times.)

REVERSE()
This function reverses a string. It takes one argument as string to reverse.

For example,

SELECT REVERSE('Peter Scott') AS [Name];
Result: ‘ytnahoM timA’
SELECT REVERSE('Built-In Functions in SQL Server – Part One') AS [Example];
Result: ‘enO traP – revreS LQS ni snoitcnuF nI-tliuB’

SPACE()
This function returns a string of the specified number of space characters.

SELECT 'Peter' + SPACE(10) + 'Scott' AS [Name];
Result: ‘Peter          Scott’    (It added 10 spaces between the two strings)

STR()
This function converts a numeric value to a string value. It takes three arguments.
    The first argument is the number to convert to string.
    The second argument is the length of the returning string and default value is 10.
    The third argument is the number of decimals to display in the returning string and the default value is 0.

The second and the third arguments are optional. For example,

SELECT STR(10.513) result;
Result: ‘11’    (result is rounded because we didn’t pass the decimal places so it takes defaults as 0)
SELECT STR(10.513, 5, 2) result;
Result: ‘10.51’

STUFF()
This function removes a part of a string and then inserts another part into the string, in a specified position. It takes four arguments. The first argument is the string to be processed or modified. The second argument is the position in string to start deletion and insertion of some characters. The third argument is the number of characters to delete from string. The fourth argument is the new sub-string to replace into string at the start position. For example,

SELECT STUFF('My name is ', 11, 1, ' Peter Scott!');
Result: ‘My name is Peter Scott!’
SELECT STUFF('My name is ', 1, 1, ' Peter Scott!');
Result: ‘Peter Scott!y name is’

SUBSTRING()
This function extracts a substring with a specified length starting from a position in a string. It takes three arguments. The first argument is the string from which we extract a character or sub-string. The second argument specifies the position where the returned substring starts. The third argument is the number of characters of the substring to be returned ant it must be a positive number. For example:

SELECT SUBSTRING('Built-In Functions in SQL Server – Part One', 4, 16) AS ResultString;
Result: ‘lt-In Functions’    (we get the string starting index from 4 to no of 16 characters)
SELECT SUBSTRING('Built-In Functions in SQL Server – Part One', 10, 16) AS ResultString;
Result: ‘Functions in SQL’

Date and Time Function
CURRENT_TIMESTAMP

This function returns the current date and time, in a “YYYY-MM-DD hh:mm:ss.mmm” format. For example:

SELECT CURRENT_TIMESTAMP;
Result: ‘2021-12-27 13:43:09.640’   (Date Time in “YYYY-MM-DD hh:mm:ss.mmm” format)

DATEADD()
This function adds a time/date interval to a input date and then returns the modified date. It takes three arguments. The first argument is the time/date interval to which we will add value. The second argument is the number of interval to be added to first argument. It can be positive or negative number. The third argument is the date that will be modified.

For example,
SELECT DATEADD(YEAR, 2, '2021-12-25 13:50:47.234') AS [DateAdd];
Result: ‘2023-12-25 13:50:47.233’
SELECT DATEADD(MONTH, 2, '2021-12-25 13:50:47.234') AS [DateAdd];
Result: ‘2022-02-25 13:50:47.233’
SELECT DATEADD(DAY, 2, '2021-12-25 13:50:47.234') AS [DateAdd];
Result: ‘2021-12-27 13:50:47.233’
SELECT DATEADD(WEEK, 2, '2021-12-25 13:50:47.234') AS [DateAdd];
Result: ‘2022-01-08 13:50:47.233’
SELECT DATEADD(HOUR, 2, '2021-12-25 13:50:47.234') AS [DateAdd];
Result: ‘2021-12-25 15:50:47.233’
SELECT DATEADD(MINUTE, 2, '2021-12-25 13:50:47.234') AS [DateAdd];
Result: ‘2021-12-25 13:52:47.233’
SELECT DATEADD(SECOND, 30, '2021-12-25 13:50:47.234') AS [DateAdd];
Result: ‘2021-12-25 13:51:17.233’
SELECT DATEADD(MILLISECOND, 200, '2021-12-25 13:50:47.234') AS [DateAdd];
Result: ‘2021-12-25 13:50:47.433’

DATEDIFF()
This function returns the difference between two dates in years, months, weeks, etc. It takes three arguments.

The first argument is “datepart” which is the part of date like a year, a month, a week, a day etc.

The second and third arguments are “startdate” and “enddate” to be compared.

For example,
SELECT DATEDIFF(YEAR, '2020/10/13', '2021/10/13') AS [DiffYear];
Result: ‘2’
SELECT DATEDIFF(MONTH, '2020/10/13', '2021/09/13') AS [DiffMonth];
Result: ‘11’
SELECT DATEDIFF(HOUR, '2020/10/13 07:00', '2021/10/13 12:45') AS [DiffHour];
Result: ‘8765’

DATEFROMPARTS()
This function returns a date from the specified parts like year, month, and day values. For example:

SELECT DATEFROMPARTS(2021, 12, 31) AS [DateFromParts];
Result: ‘2021-12-31’

DATENAME() & DATEPART()
The DATENAME() and DATEPART() function returns a specified part of a date. But the DATENAME() function returns the result as string value and DATEPART() return the result as integer value.

SELECT DATENAME(MONTH, '2021/12/25') AS [DateNameMonth],
       DATENAME(WEEKDAY, '2021/12/25') AS [DateNameDay];
Result: ‘December, Saturday’
SELECT DATEPART(MONTH, '2021/12/25') AS [DatePartMonth],
       DATEPART(WEEKDAY, '2021/12/25') AS [DatePartDay];
Result: ‘12, 7’

DAY(), MONTH() & YEAR()
The DAY() function returns the day of the month for a specified date. The value is from 1 to 31.

The MONTH() function returns the month part for a specified date. The value is from 1 to 12.

The YEAR() function returns the year part for a specified date.

SELECT DAY('2021-12-25') AS [Day];
Result: ‘25’
SELECT MONTH('2021-12-25') AS [Month];
Result: ‘12’
SELECT YEAR('2021-12-25') AS [Year];
Result: ‘2021’

GETDATE(),GETUTCDATE() & SYSDATETIME()
The GETDATE() function returns the current database date and time, in a “YYYY-MM-DD hh:mm:ss.mmm” format.

The GETUTCDATE() function returns the current database date and time in UTC, in a “YYYY-MM-DD hh:mm:ss.mmm” format.

The SYSDATETIME() function returns the date and time of the computer where the SQL Server instance is running.

SELECT GETDATE() AS [GetDate], GETUTCDATE() AS [UTCDate], SYSDATETIME() AS [SysDateTime];
Result: ‘2021-12-27 15:06:35.127, 2021-12-27 09:36:35.127, 2021-12-27 15:06:35.1283952’

ISDATE()
This function checks an expression is valid date or not. It returns 1 if it is a valid date, otherwise 0.
SELECT ISDATE('2021-12-25') AS [STATUS];
Result: ‘1’ (returns 1 because it’s a valid date)
SELECT ISDATE('2021-15-25') AS [STATUS];
Result: ‘0’ (returns 0 because not a valid date)

In the above article, we learned how to use string, date and time built-in functions in SQL Server. Hope this will help the readers.

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Usually, we install SQL Server by default, it works just fine. However, sometimes, we might face some problems in the new version installation. I got an issue when I installed the SQL Server Developer Edition 2019, that is related to a PolyBase issue.  This article will introduce the problem, the reason and the fix. (SQL Server 2019 Developer Edition Installation see here)

Once in 2020, after I installed an instance of SQL Server 2019 Developer Edition, I found my machine hard disk was eaten very fast. The following is what I met this situation again early this year, one can see the hard disk reduced close to 100 GB in just one day.

Reason
I am not SQL Server database administrator, I do not want to debug it, and I do not care about the real reason, I just want to have a fix on it. By online searching, I found the solution from one excellent article, in which one can get the real reason and debugging process, what I will introduce here is just the conclusion.

The problem is caused by, in our installation, we installed this component: PolyBase

and configure it like this:

I do not know what this component is for, and the installation is successfully completed:

However, there is an issue with this component.  If we open service, we can see that the PolyBase components are always in the starting status, which means they always cannot be started:


The issue is caused by that these components need to connect to SQL Server by TCP provider, however, the TCP/IP as a network protocol for SQL server is unable by default.  This can be seen by opening the Computer Management:

Therefore, the SQL server will report this problem automatically in log file, about every half an hour making a dump file that is about 400 MB, which will eat the hard disk 20~30 GB every day.

Fix
Simply make the SQL Server TCP/IP protocol enabled like this:

After restarting the SQL Server and the PolyBase service, you will see the PolyBase components are running.

Then there will be no more garbage dump files created in the SQL Server log folder. And, you probably need to manually delete the previous dump files to get the lost space back.

This bug is fixed and the main idea is from the article below in reference, thanks a lot for the Author. If anyone has an interest in the technical details for this issue, you can read this article.

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Have you ever come across a situation where you need to check first if a table exists? Or have you come across a scenario where you need to check if the table's column exists?  Then alter the table by adding your desired column. If you have answered yes to any of these two, you came to the right place.

This post will explore the INFORMATION_Schema views, learn what it is, and show you some of its common usages.

By the way, I'll be using SQL Server 2016, but it can also be applied with other older and later versions of SQL Server.
What is INFORMATION_SCHEMA Database?

The INFORMATION_SCHEMA stores other databases' details on the server.

It gives you the chance to retrieve views/information about the tables, views, columns, and procedures within a database.

The views are stored in the master database under Views->System Views and will be called from any database you choose.

Let's see a screenshot below,

Benefits
As a database developer or administrator, understanding schema and what tables are in a specific database gives us a good idea what's the underlying structure, which can help you write SQL queries. It also allows us to check if everything is expected or on the database. Moreover, it also helps us avoid running queries multiple times to see if the schema name or column name is correct.

Common Usages
Before we start, we'll be using the Northwind database for all our examples. You can download it from here. Now, here are the steps we're going to take. First, get all the databases on our local SQL Server instance, get all the tables, third, let's search for a column, fourth search for constraints, and the last query some views.
Showing All Databases

Let's try to show first all of the databases on a current server instance that we're in.

Note that my result will differ from yours, but you'll see all the databases on your SQL Server instance once you run the query below.
SELECT * FROM sys.databases;
EXEC sp_databases;

Output

The syntax on how we were able to show the database isn't directly related to INFORMATION_Schema.

However, it is an excellent start for us as we go through from database to tables to columns to keys.
Showing All Tables

Now that we have an idea of getting the database on a SQL Server instance.

In this section, we will try to get all of the possible tables of the Northwind database.
USE [Northwind];
--show all table
SELECT * FROM INFORMATION_SCHEMA.Tables;   

Querying Column of a Specific Table

In this example, we'll explore how to check a table and then a column if it exists.

Then add a new column to the categories table. Then let's set Tags as its column name and set its data type as NVARCHAR(MAX).

Let's try to see a sample query below.

USE [Northwind];

/*
 * Let's try to declare some variables here that we can use later when searching for them.
 */
DECLARE @TABLE_NAME NVARCHAR(50);
SET @TABLE_NAME = 'Categories';

DECLARE @COLUMN_NAME NVARCHAR(50);
SET @COLUMN_NAME = 'Tags';

IF EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE
                    TABLE_NAME = @TABLE_NAME)
    BEGIN

        PRINT CONCAT('1. Categories table does exists.',
                    CHAR(13), '1.1 Let''s now create the Tags column.');

        IF EXISTS (SELECT * FROM INFORMATION_SCHEMA.COLUMNS
                    WHERE TABLE_NAME = @TABLE_NAME
                    AND COLUMN_NAME = @COLUMN_NAME)
            BEGIN
                PRINT '2. Dropping the Tags column of the Categories table.';
                ALTER TABLE [Categories]
                DROP COLUMN [Tags];
            END

        BEGIN
            PRINT '3. Creating the Tags column of the Categories table.';

            ALTER TABLE [Categories]
            ADD [Tags] NVARCHAR(MAX);

            DECLARE @ADDED_COLUMNS NVARCHAR(MAX);

            SET @ADDED_COLUMNS = CONCAT('4. Categories table columns: ',
                                        (SELECT STRING_AGG(COLUMN_NAME, ',')
                                        FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = @TABLE_NAME));

            PRINT @ADDED_COLUMNS;
        END
    END
ELSE
    BEGIN
        PRINT 'CATEGORY TABLE DOESN''T EXISTS';
    END

Going to the example above, as you can see, we have to check if the Categories-table exists. Then from that, we did check if the Tags column does exist. If it does, we need to drop the existing column. And after that, we have re-created the Tags column. Lastly, we have shown all the Categories-table columns by a comma-separated list.

Just a note, the STRING_AGG function is a function that can be applied to SQL Server 2017 and later.

Output

Find Foreign Keys, Primary Key, and Check Constraint in a Table

Let's see how we can query the primary key, foreign key and check the constraint of a specific table.

In this case, we're just going to use the [Order Details] table and show the constraints such as primary key, foreign key, and check constraint.

Let's see the query below.

USE [Northwind];

SELECT CONSTRAINT_TYPE, CONSTRAINT_NAME
FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
WHERE CONSTRAINT_TYPE IN ('PRIMARY KEY', 'FOREIGN KEY', 'CHECK')
AND TABLE_NAME = 'Order Details';

Querying Views
In this last section, we'll make a simple query that will show the Views inside the Northwind database.

Let's see the query below.

USE [Northwind];

SELECT TABLE_CATALOG AS 'Database Name',
       TABLE_NAME AS 'View Name',
       View_Definition as 'Query'
FROM INFORMATION_SCHEMA.VIEWS
WHERE TABLE_NAME  LIKE 'Products%'

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In this article, we will see how to use the cast and convert functions in SQL Server 2012. The cast and convert functions provide similar functionality. They are used to convert a value from one data type to another. So let's take a look at a practical example. The example is developed in SQL Server 2012 using the SQL Server Management Studio.

Cast() Function in SQL Server
The Cast() function is used to convert a data type variable or data from one data type to another data type. The Cast() function provides a data type to a dynamic parameter (?) or a NULL value.

Syntax
CAST ( [Expression]
AS Datatype)

The data type to which you are casting an expression is the target type. The data type of the expression from which you are casting is the source type.

Example 1
     DECLARE @A varchar(2)  
    DECLARE @B varchar(2)  
    DECLARE @C varchar(2)  
    set @A=25  
    set @B=15  
    set @C=33  
    Select CAST(@A as int) + CAST(@B as int) +CAST (@C as int) as Result

Example 2
    DECLARE @Z char(30)  
    SELECT @Z=current_timestamp  
    select CAST (@Z as date) as result  

Convert() Function in SQL Server
When you convert expressions from one type to another, in many cases there will be a need within a stored procedure or other routine to convert data from a datetime type to a varchar type. The Convert function is used for such things. The CONVERT() function can be used to display date/time data in various formats.

Syntax
CONVERT(data_type(length), expression, style)
Style - style values for datetime or smalldatetime conversion to character data. Add 100 to a style value to get a four-place year that includes the century (yyyy).
 
Example 1
In this example we take a style value 108 which defines the following format:
hh:mm:ss
 
Now use the above style in the following query:
    select convert(varchar(20),GETDATE(),108)  

Convert() Function in SQL Server
When you convert expressions from one type to another, in many cases there will be a need within a stored procedure or other routine to convert data from a datetime type to a varchar type. The Convert function is used for such things. The CONVERT() function can be used to display date/time data in various formats.
Syntax

CONVERT(data_type(length), expression, style)
Style - style values for datetime or smalldatetime conversion to character data. Add 100 to a style value to get a four-place year that includes the century (yyyy).
 
Example 1
In this example we take a style value 108 which defines the following format:
hh:mm:ss
 
Now use the above style in the following query:
    select convert(varchar(20),GETDATE(),108)  

In this example we use the style value 107 which defines the following format:

Mon dd, yy

Now use that style in the following query:
    select convert(varchar(20),GETDATE(),107)

Example 2
In this example we see different style values which defines the following format.
    SELECT CONVERT(VARCHAR(15),GETDATE(),6)  
    go  
    SELECT CONVERT(VARCHAR(16),GETDATE(),106)  
    go  
    SELECT CONVERT(VARCHAR(24),GETDATE(),113)

    select convert(varchar(20),GETDATE(),108)  

Example 3
In this example we use the style value 107 which defines the following format:

Mon dd, yy

Now use that style in the following query:
    select convert(varchar(20),GETDATE(),107)

Example 4
In this example we see different style values which defines the following format.
    SELECT CONVERT(VARCHAR(15),GETDATE(),6)  
    go  
    SELECT CONVERT(VARCHAR(16),GETDATE(),106)  
    go  
    SELECT CONVERT(VARCHAR(24),GETDATE(),113)  

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I am going to take advantage of this time to write code for a split comma separated string without using functions. In general, we face this type of scenario in real working conditions, and we can expect this in interview questions. Now, I came up with different resolutions for this. We can use Recursive CTE to split a  comma-separated string in SQL. Instead of a string, we can use columns in our tables also. In my current project, I got raw data in a comma-separated string format, and I used it to split the string into rows and insert them into my tables.
    declare @a  varchar(100)  
      
    set @a = 'Peter,Hello,HI'  
      
      
    ;with cte as(select STUFF(@a,1,CHARINDEX(',',@a),'') as number,  
    convert(varchar(50),left(@a, CHARINDEX(',',@a)-1 )) col1  
    union all  
      
    select STUFF(number,1,CHARINDEX(',',number+','),'') number,  
    convert(varchar(50),left(number,(case when CHARINDEX(',',number) = 0 then len(number) else CHARINDEX(',',number)-1 end)) )col1  
      
    from cte where LEN(number) >0  
    )  
    select col1 from cte  

My string contains 4 words and is separated by a comma. I want to split 4 words into 4 rows. In the above code, I used Recursive CTE to achieve my goal. The first part was to hide the first word in a string in the Number column and the hidden word will appear in the Col1 column. The second part of the Cte was to use the output of the number column in the first part and split that string accordingly. After executing the above code we get results.

I have another approach to achieve the same result. If you are familiar with XML, the below command can be placed directly in your join and where conditions as well.
    declare @a  varchar(100)  
      
    set @a = 'peter,Hello,HI'   
      
    select   
        a.value('.', 'varchar(max)')   
    from  
        (select cast('<M>' + REPLACE(@a, ',', '</M><M>') + '</M>' AS XML) as col) as A  
        CROSS APPLY A.col.nodes ('/M') AS Split(a)  

After executing this code, you get the same result shown above. 

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This small article is intended for the audience stuck in their interview when asked for the differences among CHAR, VARCHAR, NCHAR and NVARCHAR data types. Actually it is simple but sometimes people get confused.

To store data as characters, numeric values and special characters in a database, there are 4 data types that can be used. So what is the difference among all 4 of these data types?

• CHAR vs VARCHAR
• NCHAR vs NVARCHAR

Considering an example, we will look into each one of them.
    DECLARE @string CHAR(20)  
   SET @string = 'Robin'  
   SELECT @string AS 'String', DATALENGTH(@string) AS 'Datalength' , LEN(@string) AS 'Len'  

Note: The LEN() method provides the length of a character excluding trailing blanks stored in the string expression whereas the DATALENGTH() method provides the number of byte spaces occupied by the characters in a string expression.
 
As you know we represent the character values within single quotes, for example 'Robin'. But do you know we can represent these same characters within double quotes similar to programming languages representing a string, for example “Robin”? This can be done by setting the value:
    SET QUOTED_IDENTIFIER OFF

By default, it is set to ON
 
CHAR vs VARCHAR
Talking about the CHAR data type:
    It is a fixed length data type
    Used to store non-Unicode characters
    Occupiers 1 byte of space for each character

If the value provided to a variable of CHAR data type is shorter than the length of a column of declared the size of the variable, then the value would be right-padded with blanks to match the size of column length.
    DECLARE @string CHAR(20)  
    SET @string = 'Robin'  
    SELECT @string AS 'String', DATALENGTH(@string) AS 'Datalength' , LEN(@string) AS 'Len'

As you can see above, the bytes occupied by the variable are 20 even though the length of the characters is 5. That means that irrespective of the character stored in the column, it will occupy all bytes to store the value.

About the VARCHAR data type:
    It is a variable length data type
    Used to store non-Unicode characters
    Occupies 1 byte of space for each character

    DECLARE @string VARCHAR(20)  
    SET @string = 'Robin'  
    SELECT @string AS 'String', DATALENGTH(@string) AS 'Datalength' , LEN(@string) AS 'Len'

As you can see above, it is showing DATALENGTH as 5 which means it will use only the number of bytes equal to the number of characters. This will allow me to avoid wasting database space.

Note:  If SET ANSI_PADDING is OFF when CREATE TABLE or ALTER TABLE is executed, a CHAR column defined as NULL is considered as VARCHAR.

When to use what?
If you are sure about the fixed length of the data that would be captured for any specific column then go for CHAR data type and if the data may vary then go for VARCHAR.
 
NCHAR vs NVARCHAR
Similar to CHAR data type, the NCHAR data type:
    Is a fixed length data type
    Used to store Unicode characters (for example the languages Arabic, German and so on)
    Occupies 2 bytes of space for each character

    DECLARE @string NCHAR(20)  
    SET @string = 'Robin'  
    SELECT @string AS 'String', DATALENGTH(@string) AS 'Datalength' , LEN(@string) AS 'Len'

As you can see above, the data length column shows 40 bytes even though the size declared is 20. It's because NCHAR holds 2 bytes of space for each character.

About the NVARCHAR data type:
    It is a variable-length data type
    Used to store Unicode characters
    Occupies 2 bytes of space for each character
    DECLARE @string NVARCHAR(20)  
    SET @string = 'Robin'  
    SELECT @string AS 'String', DATALENGTH(@string) AS 'Datalength' , LEN(@string) AS 'Len'

As in the output above, you will observe DATALENGTH column is showing only 10 as a value. That is because it occupies 2 bytes of space for each character and the data length is only 5 characters, therefore it will occupy 10 bytes of space in the database.

When to use what?
If your column will store a fixed-length Unicode characters like French, Arabic and so on characters then go for NCHAR. If the data stored in a column is Unicode and can vary in length, then go for NVARCHAR.
 
Querying to NCHAR or NVARCHAR is a bit slower then CHAR or VARCHAR. So don't go for NCHAR or NVARCHAR to store non-Unicode characters even though this data type supports that.

This small article is just to make you aware of the differences among the CHAR, VARCHAR, NCHAR and NVARCHAR data types since they are all used to store characters, numbers or special characters. I hope you like this small article and will that it will be helpful to you at some point of time. Leave your comments whether its good or bad. Sharing is valuable no matter what.

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SQL Server Log Shipping is one of the basic levels of SQL Server High-Availability (HA) features. It is an automated system/way to keep backup & restore your database from one server/instance to another or more server/instances. The primary purpose of log shipping is to increase database availability by maintaining a backup server that can replace a production server quickly.

Limitation of Log Shipping

• SQL Server Log Shipping is one of the basic level of SQL Server High-Availability (HA) features.
• Here is the possibility of data loss in log shipping for a set of times you’ve set for log shipment to the primary server to the secondary server(s) when the primary server fails on a disaster.
• Failover does not work for log shipping.
• SQL Server Express edition does not support log shipping.

Benefits of Log Shipping

• Easy setup and maintenance.
• Provides both Disaster Recovery and High Availability solutions.
• Low maintenance.
• Multiple standby servers can be configured.
• Standby databases can be available for read-only queries
• From SQL Server 2008 Log Shipping technology is available in all later SQL Server Version except express edition.
• Log Shipping allows the auto-update of the schema(table, views, etc.) on a secondary server.
• Let’s see how the log shipping technology works in the following diagram.

Development/Tested Environment Details

Note
Though, Here we’ve used different editions of SQL Server (Enterprise & Developer) but it is good practice to keep the same version & same edition of SQL Server in both/all server(s).

Configure SQL Server Log Shipping(Without active directory)

Follow the steps one by one to configure SQL Server Log Shipping(Without active directory).

Step 1

Create a folder on your Primary Server. Then go to Properties > Sharing Tab > Click On Share > Select Everyone > Click On Add > Give it Read/Write Permission > finally click on Share.

Step 2
Do the same thing on your Secondary Server as in Step 1.

Step 3
As we’re going to setup Log Shipping without using Active Directory (AD), To do that we need to create a user with the same name and password in both servers (Primary & Secondary), so that we can use them for SQL Server Service & SQL Server Agent Service read/write permission. First create a new user on your Primary Server.

To create a new User go to Start > Settings > Accounts

The following screen will appear. Then follow the following steps

Now we’ll create a user without a Microsoft account.

Provide the required field and click on Next Button. Hope User will be created.

Step 4
Do the same thing on your Secondary Server as in Step 3.

Note: Keep the user name & password the same as Primary Server you’ve saved.

Step 5
Now we’ll give MSSQLSERVER / SQL Server(Version) and SQL Server Agent (Version) permission/log on with our recently created user in both (primary & secondary) servers. For doing that follow the following steps. Go to Run (Windows Key + R) and Type services.msc as like the following image.

Then following window/screen will be arrived. Then Select SQL Server(MSSQLSERVER) > Right-click on that > Click On Properties as following image.

When you click on Properties following screen will come up on your screen. Click on Log On tab & then click on the Browse as per the following image(s).

Step 6
Do the same thing on your Primary Server for SQL Server Agent as in Step 5.

Step 7
Do the same thing on your Secondary Server as Step 5 & Step 6.

Note: Keep the user name & password the same for SQL Server service log on as Primary Server you’ve saved. And also make sure MSSQLSERVER & SQL Server Agent Service is running on your both server. For confirmation, you may restart these services in primary

Step 8
We’re almost done with all other environment settings except SQL Server. Now log on your primary server(SQL Server) with a user(Like: user = ***** , Password= *****).
Note: Your login user must have the sysadmin role. Right Click on your desired Database and click on Properties.

Step 9
Now take a full backup of that database. And take the backup file to the secondary server & restore it as the following image. Here I’m not showing the full backup process but after selecting the database (.bak) file, you’ve to go Option > Then select “RESTORE WITH NORECOVERY”.

Step 10
Now we’ll create the main things/configurations for our desired log shipping. Go to the primary server and select your database. Now follow these following images one by one.

After clicking on Properties following screen will be open. Now follow the marked serial.

After Clicking on Backup Settings following screen will appear. Now follow the marked step one by one as a mentioned serial.

When you click on the Schedule button following screen will appear. Here you can set up the necessary configuration(s). Here we’ll change only the marked field value.

After setting(s) all changes/configurations click OK. Then the following screen will appear. Now click OK.

After clicking on OK from the previous screen the following screen will open. Now Click On Add as marked in the following screen.

When you click on Add in the previous screen then the following screen will be come-up. Now it’s time to connect with your secondary server(s)/instance(s). Now follow the marked steps & provide the necessary data.

In the following image first tab, we’ll just work on the database restore/initialing process on our secondary server. You know, we’ve already restored our database in our secondary server at Step 9. So we’ll select “No, the secondary database is initialized.” Option and click OK.  Now go to the second tab named “Copy Files”, put your secondary server shared folder network path, And click on the Schedule… button

After clicking on the Schedule… from the Copy Files tab following screen will appear. Change the marked field value as your requirement and leave others as usual if it is not necessary for you. Then click OK.

Now click on the Restore Transaction Log tab Select Standby Mode > Check on “Disconnect users in the database when restoring backups” > Put your delay restoring time (It is optional) > click on Schedule… button

After clicking on Schedule… from the Restore Transaction Log tab following screen will appear. Change the marked field value as your requirement and leave others as usual if it is not necessary for you. Then click OK.

After clicking on OK from the previous screen following image will be open. Our secondary server instance was successfully added. Now click on OK from the following image.

We’ve done all settings & configurations for our desired log shipping feature. When clicking OK from the previous screen then the following screen will open. If you’ve everything as our document, we hope you’ll be able to see the following screen with success a message. Click On the Close button.

Step 11
Congratulations, you’ve successfully configured log shipping. Now we’ll manually test, does our log shipping is working or not as our expectation. For manual testing first go to your Primary Server > Expand SQL Server Agent > Right-click on your Log Ship Backup Job > Click on Start Job at Step.

If everything is fine you’ll get a success message like the bellow image.

Now go to your secondary server. > Expand SQL Server Agent > Right-click on your Log Ship Copy Job > Click on Start Job at Step..

If everything is fine you’ll get a success message like the bellow image.

Tips: For testing data update, you may insert some data on your primary database and then you may follow the step (Step-11) for manual testing.

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Introduction
In this article, we are going to discuss STUFF and REPLACE functions in SQL Server. Also, we will discuss the differences between both of them and in which scenario it will be used.

We will cover,
    Use Case
    STUFF Function
    Replace Function
    Differences between STUFF and REPLACE

USE CASE
First, let's discuss the below use case,
Suppose we have a requirement to replace part of the string with a new string what you will do?

Your answer would be, REPLACE Function. Right?
Let me make this scenario more complex, suppose you have a string that has multiple words that are the same and you want to replace a word from a specific position. I mean only one word not all. How will you do that?

The answer would be, STUFF function.

Replace function will replace all the words so it will not fit in this case.

This is a difference between STUFF and REPLACE. REPLACE function replace all words from the text and STUFF will Replace word from a specific place.
STUFF Function in SQL Server

In SQL Server, the STUFF function deletes the sequence of the characters from the source string first and then inserts another string, starting at a given position.

Syntax
STUFF( source_string, start_position, length, another_string)

SQL
Source_string

The source string we will modify.
start_position

The start position is to delete characters from the source string.

Length

Number of characters to delete from the source string.

another_string
new string which will insert into the source string

Example 1 – Delete old string and insert a new string
Suppose I have a string "Hello All. Welcome and Nice to see you All in this article", I want to replace first ‘All’ with ‘World’.
SELECT  STUFF('Hello All. Welcome and Nice to see you All in this article',7,3,'World')

OUTPUT

Example 2 – Insert new string
I want to add a new string after "Hello" in the below example hence we have given 0 for length.
SELECT  STUFF('Hello . Welcome and Nice to see you All in this article',7,0,'World')

Example 3 – Format Date
We will change the date format from DDMMYYYY to DD/MM/YYYY using the STUFF function. This will teach you how to add nested STUFF.
SELECT STUFF(STUFF('23112021', 3, 0, '/'), 6, 0, '/') as FormattedDate;

REPLACE Function in SQL Server
The Replace function replace all occurrence within the string with a new string.

Syntax
REPLACE(original string, old_string, new_string)

Original string
This is the original string.

old_string
The string is to be replaced.

new_string
The new replacement string.

Example 4
We have replaced ‘All’ with ‘’world’.
SELECT REPLACE('Hello All. Welcome and Nice to see you All in this article','All','World')

Difference between STUFF and REPLACE
To understand the difference please see example 1 and example 4 or see below code,
SELECT  STUFF('Hello All. Welcome and Nice to see you All in this article',7,3,'World') as STUFFRESULT
SELECT REPLACE('Hello All. Welcome and Nice to see you All in this article','All','World') as REPLACERESULT

OUTPUT

In the above example, you can notice that REPLACE function replaces all the occurrences in the original string, but the STUFF function deletes a substring from the original string and inserts a new string at a given position.

I hope you enjoyed this article and find it useful.

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