MSSQL: Add support for functionality MERGE output clause (#1790)

tests/sqlparser_mssql.rs

@@ -1921,3 +1921,19 @@ fn ms() -> TestedDialects {
 fn ms_and_generic() -> TestedDialects {
     TestedDialects::new(vec![Box::new(MsSqlDialect {}), Box::new(GenericDialect {})])
 }
+
+#[test]
+fn parse_mssql_merge_with_output() {
+    let stmt = "MERGE dso.products AS t \
+        USING dsi.products AS \
+        s ON s.ProductID = t.ProductID \
+        WHEN MATCHED AND \
+        NOT (t.ProductName = s.ProductName OR (ISNULL(t.ProductName, s.ProductName) IS NULL)) \
+        THEN UPDATE SET t.ProductName = s.ProductName \
+        WHEN NOT MATCHED BY TARGET \
+        THEN INSERT (ProductID, ProductName) \
+        VALUES (s.ProductID, s.ProductName) \
+        WHEN NOT MATCHED BY SOURCE THEN DELETE \
+        OUTPUT $action, deleted.ProductID INTO dsi.temp_products";
+    ms_and_generic().verified_stmt(stmt);
+}