MySQL从最大值中选择最小值

Question

我想选择从所有表返回的最大值中的最小值。这是我用于搜索所有最大值的 sql 命令:

SELECT MAX(value) FROM temperatureTable 
UNION 
SELECT MAX(value) FROM resistanceTable 
UNION 
SELECT MAX(value) FROM pressureTable;

结果如下:

    {
        "MAX(value)": "8.113130E-1"
    },
    {
        "MAX(value)": "6.445700E+0"
    },
    {
        "MAX(value)": "6.526210E-8"
    }

如何使用sql命令选择最小值6.445700E+0？

此外，如何从返回的 Rawdatapackage 中访问 MAX(value)/MIN(value)？

result[0].Max(value) // will generate an error because of the '()'.

Answer 1

使用子查询技术:

SELECT MIN(tmp.value) 
FROM  
(   SELECT MAX(value) AS value 
    FROM temperatureTable 
UNION    
    SELECT MAX(value) AS value 
    FROM resistanceTable
UNION
    SELECT MAX(value) AS value 
    FROM pressureTable
) AS tmp