选择最少的多列

Question

我有三个名为list1,list2,list3的十进制列.我想在一个查询中找到最少三个.
我累了这个:

SELECT Least(list1, list2, list3) 
FROM   table1 

它会抛出一个least无法识别的错误函数.

Answer 1

尝试使用 UNION

SELECT MIN(x.a)
FROM
    (
        SELECT list1 a FROM table1
        UNION
        SELECT list2 a FROM table1
        UNION
        SELECT list3 a FROM table1
    ) x

更新1

SELECT ID,MIN(x.a)
FROM
    (
        SELECT ID,list1 a FROM table1
        UNION
        SELECT ID,list2 a FROM table1
        UNION
        SELECT ID,list3 a FROM table1
    ) x
GROUP BY ID

SQLFiddle演示