Ms sql updating multiple rows Adult camwork


29-Jun-2019 04:19

If the column is in a primary key, the old key value is no longer valid, and foreign keys referencing the old value are no longer valid.

If the table is referenced in a dynamic cursor, all updates change the position of the rows in the cursor.

If the column is in an index key, all updates to the data row also generate updates of the index. This feature will be removed in a future version of Microsoft SQL Server.

Avoid using this feature in new development work, and plan to modify applications that currently use this feature.

If there are two WHEN MATCHED clauses, then one must specify an UPDATE action and one must specify a DELETE action. For any given row, the second WHEN NOT MATCHED BY SOURCE clause is only applied if the first is not.

If there are two WHEN NOT MATCHED BY SOURCE clauses, then one must specify an UPDATE action and one must specify a DELETE action. For more information about table hints, see Table Hints (Transact-SQL).

For example, assume that you create a table named DECLARE @t TABLE (my Key int); UPDATE My Test SET my Value = 2 OUTPUT Key INTO @t(my Key) WHERE my Key = 1 AND RV = my Value; IF (SELECT COUNT(*) FROM @t) = 0 BEGIN RAISERROR ('error changing row with my Key = %d' ,16 -- Severity.

,1 -- State ,1) -- my Key that was changed END; CREATE TABLE My Test2 (my Key int PRIMARY KEY ,my Value int, TS timestamp); GO INSERT INTO My Test2 (my Key, my Value) VALUES (1, 0); GO INSERT INTO My Test2 (my Key, my Value) VALUES (2, 0); GO DECLARE @t TABLE (my Key int); UPDATE My Test2 SET my Value = 2 OUTPUT Key INTO @t(my Key) WHERE my Key = 1 AND TS = my Value; IF (SELECT COUNT(*) FROM @t) = 0 BEGIN RAISERROR ('error changing row with my Key = %d' ,16 -- Severity.

Performance Tip: The conditional behavior described for the MERGE statement works best when the two tables have a complex mixture of matching characteristics.

ON Caution It is important to specify only the columns from the target table that are used for matching purposes.