sql 联表更新

mysql:

 

SELECT * FROM tablename as a LEFT JOIN xdn_v2.menu as m ON m.old = CONCAT(filed1,str,filed2,field3);
UPDATE tablename1 as a,tablename2.menu as m set a.Menu = m.id WHERE m.old = CONCAT(filed1,str,filed2,field3);

 

sqlite:

注:字符串使用   ||  拼接

update table1
set  num1 = (select num2 from table2 where table2.pid=table1.id)
where...

更新多个字段时：

update table1
set  num1 = (select num2 from table2 where table2.pid=table1.id),
num11 = (select num22 from table2 where table2.pid=table1.id)
where...

 

（2）where时，也一样，比如我就将上面的改一下

update table1
set  num = 99
where table1.id=(select pid from table2 where table2.pid=table1.id)