MySQL

您实际上可以通过以下两种方式之一执行此操作：

MySQL更新联接语法：

UPDATe tableA aINNER JOIN tableB b ON a.name_a = b.name_bSET validation_check = if(start_dts > end_dts, 'VALID', '')-- where clause can go here

ANSI SQL语法：

UPDATE tableA SET validation_check =     (SELECT if(start_DTS > end_DTS, 'VALID', '') AS validation_check        FROM tableA        INNER JOIN tableB ON name_A = name_B        WHERe id_A = tableA.id_A)

选择最适合您的那个。