内部加入更新

Question

我目前正试图弄清楚如何让它发挥作用。

    UPDATE 
systems AS C 
SET C.nulled = '1' 
FROM systems 
INNER JOIN systems AS P 
ON C.nullif = P.sid 
WHERE P.status = 1

如果我正确地做到这一点，我不是100％。如果P.sid等于C中的nullif列，我想将C.null更新为1.

Answer 1

这是正确的语法

UPDATE systems AS C 
  INNER JOIN systems AS P 
  ON C.nullif = P.sid 
SET C.nulled = '1' 
WHERE P.status = 1

Answer 2

正确的语法：

UPDATE `systems` AS `C`
INNER JOIN `systems` AS `P`
    ON `C`.`nullif`=`P`.`sid`
SET `C`.`nulled`='1' 
WHERE `P`.`status`=1