In this blog, I will explain SQL Constraints. They are used to specify rules for the data in a table. The following SQL Constraints are commonly used (Primary key, foreign key, unique key, Composite key, null, Not Null, check).

Primary Key
The Primary key must contain be a unique value. It is the primary column and can’t have the null value. It uniquely identifies each row in a database table.
 
Syntax
    CREATE TABLE TB_NAME(Column1 datatype,column2 datatype PRIMARY KEY(Column1)) 

Foreign Key
1. Foreign key always refers to the primary key column.
2. Foreign key accepted to duplicate value.
 
Syntax
    CREATE TABLE TB_NAME(column1 datatype FOREIGN KEY REFERENCES(primary_key column_name),cloumn2 datatype) 

Unique Key
 
The unique key is the same as the primary key, but one row is accepted for the null value.
 
Syntax
    CREATE TABLE TB_NAME(Column_name datatatype UNIQUE,column_name2 datatype) 

Composite key
A composite key is a set of multiple keys that, together, uniquely identifies each record
 
Syntax
    CREATE TABLE TB_NAME(Column1 datatype,column2 datatype PRIMARY KEY(Column1,column2)) 

Not Null
Forces a column not to accept NULL values
 
Syntax
    CREATE TABLE TB_NAME(Column1 datatype,column2 datatype NOT NULL) 

Check
The CHECK constraint is used to limit the value range that can be placed in a column.
 
Syntax
    CREATE TABLE TB_NAME(MARKS INT CHECK(MARKS<=100))

Version control helps you to track the changes of a code repository. But, it doesn't much help to track database changes. General practice is to create a single script file that includes all the schema and update that file every time you make any changes into the database and commit it to version control. However, this is a bit longer a way to track the changes. Another way is to use popular tools like Red Gate Change Automation. But there is a native way around to handle tracking! simply put, DDL trigger can be used to track the DB changes.

Track Stored Procedure changes using DDL trigger

Here we'll see how to track stored procedure changes using DDL trigger.

Create your audit database and create a table.  
USE AuditDB;  
GO  
 
CREATE TABLE dbo.ProcedureChanges  
(  
    EventDate    DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,  
    EventType    NVARCHAR(100),  
    EventDDL     NVARCHAR(MAX),  
    DatabaseName NVARCHAR(255),  
    SchemaName   NVARCHAR(255),  
    ObjectName   NVARCHAR(255),  
    HostName     NVARCHAR(255),  
    IPAddress    VARCHAR(32),  
    ProgramName  NVARCHAR(255),  
    LoginName    NVARCHAR(255)  
);   
Add data of all existing stored procedures from your actual database (Product DB in this example)
USE ProductDB;  
GO  
 
INSERT AuditDB.dbo.ProcedureChanges  
(  
    EventType,  
    EventDDL,  
    DatabaseName,  
    SchemaName,  
    ObjectName  
)  
SELECT  
    N'Initial control',  
    OBJECT_DEFINITION([object_id]),  
    DB_NAME(),  
    OBJECT_SCHEMA_NAME([object_id]),  
    OBJECT_NAME([object_id])  
FROM  
    sys.procedures;  
Create DDL trigger to capture changes
USE ProductDB;  
GO  
 
CREATE TRIGGER CaptureStoredProcedureChanges  
    ON DATABASE  
    FOR CREATE_PROCEDURE, ALTER_PROCEDURE, DROP_PROCEDURE,   
    ALTER_SCHEMA, RENAME  
AS  
BEGIN  
    SET NOCOUNT ON;  
 
    DECLARE @EventData XML = EVENTDATA(), @ip VARCHAR(32);  
 
    SELECT @ip = client_net_address  
        FROM sys.dm_exec_connections  
        WHERE session_id = @@SPID;  
 
    INSERT AuditDB.dbo.ProcedureChanges  
    (  
        EventType,  
        EventDDL,  
        SchemaName,  
        ObjectName,  
        DatabaseName,  
        HostName,  
        IPAddress,  
        ProgramName,  
        LoginName  
    )  
    SELECT  
        @EventData.value('(/EVENT_INSTANCE/EventType)[1]',   'NVARCHAR(100)'),   
        @EventData.value('(/EVENT_INSTANCE/TSQLCommand)[1]', 'NVARCHAR(MAX)'),  
        @EventData.value('(/EVENT_INSTANCE/SchemaName)[1]',  'NVARCHAR(255)'),   
        @EventData.value('(/EVENT_INSTANCE/ObjectName)[1]',  'NVARCHAR(255)'),  
        DB_NAME(), HOST_NAME(), @ip, PROGRAM_NAME(), SUSER_SNAME();  
END  
GO  

Modify any stored procedure and check the ProcedureChanges table from AuditDB.

The method might have some limitations, but this is the simplest way to tracking changes of small size databases.