A way of writing SQL, update when matching, or insert

grammar ：

MERGE INTO (  ) A 
  USING (
      
    ) B ON ( ) 

 WHEN MATCHED THEN 
        Write update statements or other statements ：UPDATE  SET ....

 WHEN NOT MATCHED THEN  

     Write insert statements or other statements ：
    INSERT (  Field   ) VALUES(    data source  );

 

analysis ：

MERGE INTO (  Query all the data  ) A 
  USING (
        Query the data to be compared or matched SQL
    ) B ON ( Data matching or comparison , such as  A = B ) 

 WHEN MATCHED THEN  --  The meaning of this match is to update the statement 
        Write update statements or other statements ：UPDATE  SET ....

 WHEN NOT MATCHED THEN  --  This means that the insert statement is executed after the mismatch 

     Write insert statements or other statements ：
    INSERT (  Field   ) VALUES(    data source  );

 

Search for

Copy

MERGE INTO (  Query all the data  ) A 
    USING (
	
        Query the data to be compared or matched SQL

	) B ON ( Data matching , such as  A = B ) 

   WHEN MATCHED THEN  --  The meaning of this match is to update the statement 
        Write update statements or other statements ：UPDATE 
	SET ....

  WHEN NOT MATCHED THEN  --  This means that the insert statement is executed after the mismatch 

     Write insert statements or other statements ：
	INSERT (
		 Field 
	)
VALUES
	(
		 data source 
	);

　　

MERGE INTO (  Query all the data  ) A 
    USING (
	
        Query the data to be compared or matched SQL

	) B ON ( Data matching , such as  A = B ) 

   WHEN MATCHED THEN  --  The meaning of this match is to update the statement 
        Write update statements or other statements ：UPDATE 
	SET ....

  WHEN NOT MATCHED THEN  --  This means that the insert statement is executed after the mismatch 

     Write insert statements or other statements ：
	INSERT (
		 Field 
	)
VALUES
	(
		 data source 
	);