How to track changes in database when there is something changes?

Question

Supposed that i have all privileges on a database and there is an application using that database. How to know which tables, which columns have changes in database when I do something in the screen.

This is for Windows and SQL Server 2012. We don't have database structure document. That's why i need this to trace this

Answer 1

Use

Change Data Capture

Change Tracking

or example trigger/SQL Server Profiler

Answer 2

You can create a trigger which will insert column name, old values and new values in a audit table as shown below.

CREATE TABLE [dbo].[NewAuditLog](
    [Type] [char](1) NULL,
    [TableName] [varchar](128) NULL,
    [PK] [varchar](1000) NULL,
    [FieldName] [varchar](128) NULL,
    [OldValue] [varchar](1000) NULL,
    [NewValue] [varchar](1000) NULL,
    [UpdateDate] [datetime] NULL,
    [UserName] [varchar](128) NULL
) ON [PRIMARY]

Here is that trigger

CREATE TRIGGER [dbo].[TR_Employee_AUDIT] ON [dbo].[Employee_mstr] FOR UPDATE
AS

DECLARE @bit INT ,
       @field INT ,
       @maxfield INT ,
       @char INT ,
       @fieldname VARCHAR(128) ,
       @TableName VARCHAR(128) ,
       @PKCols VARCHAR(1000) ,
       @sql VARCHAR(2000), 
       @UpdateDate VARCHAR(21) ,
       @UserName VARCHAR(128) ,
       @Type CHAR(1) ,
       @PKSelect VARCHAR(1000),
       @empcode VARCHAR(20)


--You will need to change @TableName to match the table to be audited. 
-- Here we made GUESTS for your example.
SELECT @TableName = 'Employee_Mstr'

-- date and user
SELECT         @UserName = SYSTEM_USER ,
       @UpdateDate = CONVERT (NVARCHAR(30),GETDATE(),126)

-- Action
IF EXISTS (SELECT * FROM inserted)
       IF EXISTS (SELECT * FROM deleted)
               SELECT @Type = 'U'
       ELSE
               SELECT @Type = 'I'
ELSE
       SELECT @Type = 'D'

-- get list of columns
SELECT * INTO #ins FROM inserted
SELECT * INTO #del FROM deleted

select @UserName = EMP_ModifiedBy, @empcode = emp_cd from #ins
if isnull(@UserName,'') = ''
select @UserName = EMP_ModifiedBy, @empcode = emp_cd from #del

-- Get primary key columns for full outer join
SELECT @PKCols = COALESCE(@PKCols + ' and', ' on') 
               + ' i.' + c.COLUMN_NAME + ' = d.' + c.COLUMN_NAME
       FROM    INFORMATION_SCHEMA.TABLE_CONSTRAINTS pk ,

              INFORMATION_SCHEMA.KEY_COLUMN_USAGE c
       WHERE   pk.TABLE_NAME = @TableName
       AND     CONSTRAINT_TYPE = 'PRIMARY KEY'
       AND     c.TABLE_NAME = pk.TABLE_NAME
       AND     c.CONSTRAINT_NAME = pk.CONSTRAINT_NAME

-- Get primary key select for insert
SELECT @PKSelect = COALESCE(@PKSelect+'+','') 
       + '''<' + COLUMN_NAME 
       + '=''+convert(varchar(100),
coalesce(i.' + COLUMN_NAME +',d.' + COLUMN_NAME + '))+''>''' 
       FROM    INFORMATION_SCHEMA.TABLE_CONSTRAINTS pk ,
               INFORMATION_SCHEMA.KEY_COLUMN_USAGE c
       WHERE   pk.TABLE_NAME = @TableName
       AND     CONSTRAINT_TYPE = 'PRIMARY KEY'
       AND     c.TABLE_NAME = pk.TABLE_NAME
       AND     c.CONSTRAINT_NAME = pk.CONSTRAINT_NAME

IF @PKCols IS NULL
BEGIN
       RAISERROR('no PK on table %s', 16, -1, @TableName)
       RETURN
END


SELECT         @field = 0, 
       @maxfield = MAX(ORDINAL_POSITION) 
       FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = @TableName
       AND COLUMN_NAME NOT IN ('EMP_ModifiedOn','EMP_ModifiedBy')
WHILE @field < @maxfield
BEGIN
       SELECT @field = MIN(ORDINAL_POSITION) 
               FROM INFORMATION_SCHEMA.COLUMNS 
               WHERE TABLE_NAME = @TableName 
               AND ORDINAL_POSITION > @field
               AND COLUMN_NAME NOT IN ('EMP_ModifiedOn','EMP_ModifiedBy')
       SELECT @bit = (@field - 1 )% 8 + 1
       SELECT @bit = POWER(2,@bit - 1)
       SELECT @char = ((@field - 1) / 8) + 1
       IF SUBSTRING(COLUMNS_UPDATED(),@char, 1) & @bit > 0
                                       OR @Type IN ('I','D')
       BEGIN
               SELECT @fieldname = COLUMN_NAME 
                       FROM INFORMATION_SCHEMA.COLUMNS 
                       WHERE TABLE_NAME = @TableName 
                       AND ORDINAL_POSITION = @field
                       AND COLUMN_NAME NOT IN ('EMP_ModifiedOn','EMP_ModifiedBy')
               SELECT @sql = '
insert NewAuditLog (    Type, 
               TableName, 
               PK, 
               FieldName, 
               OldValue, 
               NewValue, 
               UpdateDate, 
               UserName)
select ''' + @Type + ''',''' 
       + @TableName + ''',''' + @empcode + ''',''' + @fieldname + ''''
       + ',convert(varchar(1000),d.' + @fieldname + ')'
       + ',convert(varchar(1000),i.' + @fieldname + ')'
       + ',''' + @UpdateDate + ''''
       + ',''' + @UserName + ''''
       + ' from #ins i full outer join #del d'
       + @PKCols
       + ' where i.' + @fieldname + ' <> d.' + @fieldname 
       + ' or (i.' + @fieldname + ' is null and  d.'
                                + @fieldname
                                + ' is not null)' 
       + ' or (i.' + @fieldname + ' is not null and  d.' 
                                + @fieldname
                                + ' is null)' 
               EXEC (@sql)
       END
END

Here you do not need to specify column name manually rather it will do all it automatically.

Once table column will be updated the result will be stored in the audit table something like shown below.

Answer 3

Apart from investigating the code, SQL Server Profiler is the best way to track what is happening in your database as you use your applications. Documentation can be found here:

https://learn.microsoft.com/en-us/sql/tools/sql-server-profiler/sql-server-profiler?view=sql-server-2017