Log changes to database table with trigger

If you just want to keep a log of all transactions (insert, update and delete) in some database tables, then you can run the following script:

IF NOT EXISTS(SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME= 'Audit')
  CREATE TABLE LogTable
  (
    LogID [int]IDENTITY(1,1) NOT NULL,
    Type char(1), 
    TableName varchar(128), 
    PrimaryKeyField varchar(1000), 
    PrimaryKeyValue varchar(1000), 
    FieldName varchar(128), 
    OldValue varchar(1000), 
    NewValue varchar(1000), 
    UpdateDate datetime DEFAULT (GetDate()), 
    UserName varchar(128)
  )
GO

DECLARE @sql varchar(8000), @TABLE_NAME sysname
SET NOCOUNT ON

SELECT @TABLE_NAME= MIN(TABLE_NAME)
FROM INFORMATION_SCHEMA.Tables 
WHERE 
--query for table that you want to audit
TABLE_TYPE= 'BASE TABLE' 
AND TABLE_NAME!= 'sysdiagrams'
AND TABLE_NAME!= 'LogTable'
AND TABLE_NAME!= 'one table to not record de log';

WHILE @TABLE_NAME IS NOT NULL
  BEGIN

  SELECT 'PROCESANDO ' + @TABLE_NAME;

  EXEC('IF OBJECT_ID (''' + @TABLE_NAME+ '_ChangeTracking'', ''TR'') IS NOT NULL DROP TRIGGER ' + @TABLE_NAME+ '_ChangeTracking')


  SELECT @sql = 'create trigger ' + @TABLE_NAME+ '_ChangeTracking on ' + @TABLE_NAME+ ' for insert, update, delete
    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) ,
        @PKFieldSelect varchar(1000),
        @PKValueSelect varchar(1000)

        select @TableName = ''' + @TABLE_NAME+ '''

        -- date and user
        select @UserName = system_user ,
        @UpdateDate = convert(varchar(8), getdate(), 112) + '' '' + convert(varchar(12), getdate(), 114)

        -- 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

        -- 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 fields select for insert(comma deparated)           
        select @PKFieldSelect = coalesce(@PKFieldSelect+''+'','''') + '''''''' + 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 values for insert(comma deparated as varchar)           
        select @PKValueSelect = coalesce(@PKValueSelect+''+'','''') + ''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 @sql = ''insert LogTable(Type, TableName, PrimaryKeyField, PrimaryKeyValue, UserName)''
        select @sql = @sql + '' select '''''' + @Type + ''''''''
        select @sql = @sql + '','''''' + @TableName + ''''''''
        select @sql = @sql + '','' + @PKFieldSelect
        select @sql = @sql + '','' + @PKValueSelect
        select @sql = @sql + '','''''' + @UserName + ''''''''

        select @sql = @sql + '' from #ins i full outer join #del d''
        select @sql = @sql + @PKCols        

        exec (@sql)
    ';
  SELECT @sql
  EXEC(@sql)


  SELECT @TABLE_NAME= MIN(TABLE_NAME) FROM INFORMATION_SCHEMA.Tables 
    WHERE TABLE_NAME> @TABLE_NAME
    --query for table that you want to audit
    AND TABLE_TYPE= 'BASE TABLE' 
    AND TABLE_NAME!= 'sysdiagrams'
    AND TABLE_NAME!= 'LogTable'
    AND TABLE_NAME!= 'one table to not record de log';
END

You should be able to accomplish this using the system management views.

An example would be something like this:

SELECT er.session_id,
  er.status,
  er.command,
  DB_NAME(database_id) AS 'DatabaseName',
  user_id,
  st.text
FROM sys.dm_exec_requests AS er
  CROSS APPLY sys.dm_exec_sql_text(er.sql_handle) AS st
WHERE er.session_id = @@SPID;

I'm not sure this will be as useful to you as a more data-centric logging mechanism might be, though.

Don't forget that your logging will be part of the transaction so if there is an error and you rollback the transaction, your log will also be deleted.