Mysql查询在2个表中查找最高和最低

Question

我有两张桌子，比如tableA和tableB。两个表都有fileds，表示pointA和pointB。我需要一个查询来查找pointA和pointB列中的最高值和最低值。

 tableA
 idA    pointA
 1        20
 2        12
 3        41
 4        8     


 tableB
 idB    pointB
 1        24
 2        74
 3        2
 4        16    

我想得到像这样的结果

 HIGHEST     LOWEST
    74         2      

Answer 1

尝试：

SELECT MAX(point) as HIGHEST, MIN(point) as LOWEST
FROM
  (SELECT pointA as point FROM tableA
   UNION
   SELECT pointB as point FROM tableB) t

Answer 2

select max(pointB) AS result from tableB
union
select min(pointA) AS result from tableA

Answer 3

SELECT MAX(high) AS highest
     , MIN(low)  AS lowest
FROM
  ( SELECT MAX(pointA) AS high
         , MIN(pointA) AS low
    FROM tableA
  UNION ALL
    SELECT MAX(pointB) 
         , MIN(pointB) 
    FROM tableB
  ) AS tmp