One Statement for INSERT, UPDATE, DELETE In earlier versions of SQL Server we had to write separate statements for Insert,update and Delete based on certain conditions but now, using MERGE statement we can include the logic of such data modifications in one statement that even checks when the data is matched then just update it and when unmatched then insert it. One of the most important advantage of MERGE statement is all the data is read and processed only once. In previous versions three different statement has to be written to process three different activity (INSERT, UPDATE or DELETE), however using MERGE statement all update activity can be done in one pass of database table. This is quite an improvement in performance of database query. Syntax of MERGE statement is as following: MERGE [ TOP ( expression ) [ PERCENT ] ] [ INTO ] target_table [ WITH ( ) ] [ [ AS ] table_alias] USING ON [ WHEN MATCHED [ AND ] THEN ] [ WHEN NOT MATCHED [ BY TARGET...
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