MERGE STATEMENT in SQL Server

The MERGE statement basically works as separate insert, update, and delete statements all within the same statement. You specify a “Source” record set and a “Target” table, and the join between the two.

 MERGE INTO table_name AS T  //Target table
 USING table_name2 AS S //Source table
     ON T.column_name = S.column_name
 WHEN MATCHED THEN  
   //statement to run when match found in target
 WHEN NOT MATCHED THEN  
   //statement to run when no match found in target