sql merge used for code example

Example 1: t-sql merge example

MERGE sales.category t 
    USING sales.category_staging s
ON (s.category_id = t.category_id)
WHEN MATCHED
    THEN UPDATE SET 
        t.category_name = s.category_name,
        t.amount = s.amount
WHEN NOT MATCHED BY TARGET 
    THEN INSERT (category_id, category_name, amount)
         VALUES (s.category_id, s.category_name, s.amount)
WHEN NOT MATCHED BY SOURCE 
    THEN DELETE;

Example 2: merge clause with inner join

MERGE table1
USING (SELECT table3.keycolumn,
              table2.DataColumn1,
              table2.DataColumn2
       FROM table2
       INNER JOIN table3
           ON table2.anotherKey = table3.anotherKey
       WHERE table2.anotherKey = 'A1') tmpTable
ON 
   table1.keyColumn = tmpTable.keyColumn
WHEN MATCHED THEN
       UPDATE
       SET table1.DataColumn1 = tmpTable.DataColumn1
            ,table1.DataColumn2 = tmpTable.DataColumn2;