Question

Is there any simple way to create a column in MS SQL that will track the last time a record was updated?

I would like to have two fields. One to track when the record was created. That one is simple. Create a datetime field and set its default to getdate(). However the second field seams to be a bit more tricky. I want it to have the latest date (and time) the record was modified.

My options are:

• Include getdate() in every update statement – not an option, these tables will be accessed from MS Access
• Allow updates only through an SP. – not an option, these tables will be accessed from MS Access
• Create triggers for each table – the DB is recreated on many machines and I am afraid it will conflict or be forgotten or get out of synch.

Are there any other options?

Answer 1

Option 4:

Create a stored procedure that automatically creates triggers for all the tables in your database. In SQL 2005, optionally run this trigger any time any table is created (using a DDL trigger).

CREATE PROC UpdateTriggersCreate
AS
DECLARE
   @TableSchema sysname,
   @TableName sysname,
   @PrimaryKeys nvarchar(4000),
   @ObjectName nvarchar(4000)
   @TriggerName nvarchar(4000),
   @SQL nvarchar(4000);
SET @TableName = '';
SET @TableSchema = '';
WHILE 1 = 1 BEGIN
   SELECT TOP 1
      @TableSchema = TABLE_SCHEMA,
      @TableName = TABLE_NAME
   FROM INFORMATION_SCHEMA.COLUMNS
   WHERE
      COLUMN_NAME = 'LastUpdatedDate'
      AND (
         TABLE_SCHEMA > @TableSchema
         OR (
            TABLE_SCHEMA = @TableSchema
            AND TABLE_NAME > @TableName
         )
      )
   ORDER BY TABLE_SCHEMA, TABLE_NAME;
   IF @@RowCount = 0 BREAK;

   IF NOT EXISTS (
      SELECT *
      FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS C
      WHERE
         C.CONSTRAINT_TYPE = 'PRIMARY KEY'
         AND C.TABLE_SCHEMA = @TableSchema
         AND C.TABLE_NAME = @TableName
   ) BEGIN
       PRINT '-- Not processing table ''' + @TableSchema + '.' + @TableName + ''' because automatic last updated triggers cannot be used on tables with no primary key.';
       CONTINUE;
   END;

   SET @PrimaryKeys = NULL;
   SELECT @PrimaryKeys = Coalesce(@PrimaryKeys + ' AND T.', 'T.') + QuoteName(Y.COLUMN_NAME) + ' = I.' + QuoteName(Y.COLUMN_NAME)
   FROM
      INFORMATION_SCHEMA.TABLE_CONSTRAINTS T
      INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE Y
         ON T.CONSTRAINT_CATALOG = Y.CONSTRAINT_CATALOG
         AND T.CONSTRAINT_SCHEMA = Y.CONSTRAINT_SCHEMA
         AND T.CONSTRAINT_NAME = Y.CONSTRAINT_NAME
   WHERE
      T.CONSTRAINT_TYPE = 'PRIMARY KEY'
      AND T.TABLE_SCHEMA = @TableSchema
      AND T.TABLE_NAME = @TableName;
   -- order is not important which is good because ORDER BY is unreliable in this case

   SET @ObjectName = @TableSchema + '.' + @TableName;
   SET @TriggerName = 'TR_' + Replace(@ObjectName, '.', '_') + '_U_TimeUpdated';
   SET @SQL = 'IF Object_ID(''' + @TriggerName + ''', ''TR'') IS NOT NULL DROP TRIGGER ' + @TriggerName;
   EXEC sp_executesql @SQL;
   SET @SQL = 'CREATE TRIGGER ' + @TriggerName + ' ON ' + @ObjectName + ' FOR INSERT
AS
SET NOCOUNT ON
UPDATE T
SET T.LastUpdatedDate = GetDate()
FROM
   ' + @ObjectName + ' T
   INNER JOIN Inserted I ON ' + @PrimaryKeys;

   EXEC sp_executesql @SQL;
END;

Once you have a stored procedure like this, schedule it to run once a day or (in sql 2005 and up) in response to the DDL creation of tables.

Update 1

The code now handles schema properly, and looks up the primary keys. It also reports on and skips tables that have no primary key.

I’m not sure if I worked out all the syntax errors–I adapted it from code I’ve done this in before and didn’t actually test it. I’m sure you can figure it out.