Question

我有几个表有一个字段“version”。我想一次从所有表中选择版本的MAX值。因此，如果t1.version = 1，t2.version = 6，t3.version = 4，则返回值应为“6”。

我试过这个，但看起来错误的做法：

 SELECT MAX(t1.version, t2.version, t3.version) as maxv FROM t1, t2, t3;

在单个查询中以任何方式执行此操作？问候。

Answer 1

尝试这种方式：

select max(version)
from
(
  select version from t1
  union
  select version from t2
  union
  select version from t3
) T

Answer 2

select max(version)
from
(
  select Max(version) as version from t1
  union
  select Max(version) as version from t2
  union
  select Max(version) as version from t3
) a

来自不同表的SQL最大值

2 个答案: