有条件地选择MYSQL列

我认为您可以使用

case when then

SELECt CASE WHEN player1id = 1 THEN player2id ELSE player1id  ENDFROM players WHERe player1id =1 OR player2id=1;

或者：

SELECt CASE WHEN player1id = 1 THEN player2id WHEN player2id =1 THEN player1id  ENDFROM players WHERe player1id =1 OR player2id=1;