Question

需要从两组不同的表中选择两列。

现在我将此作为两个不同的查询但想知道是否有办法在一个查询中使用此

查询-1

 SELECT     
        BSM, DATE, HOUR, SUM(t.ATT), SUM(t.AVG_HLD)
    FROM (
        SELECT BSM, DATE, HOUR, ATT, AVG_HLD FROM t1 WHERE  ".$whereCondition." UNION ALL
        SELECT BSM, DATE, HOUR, ATT, AVG_HLD FROM t2 WHERE  ".$whereCondition." 
        ) t
    GROUP BY BSM, DATE, HOUR ";

查询-2

 SELECT     
        BSM, DATE, HOUR, SUM(s.M_ATT), SUM(s.M_AVG_HLD)
    FROM (
        SELECT BSM, DATE, HOUR, M_ATT, AVG_HLD FROM t3 WHERE    ".$whereCondition." UNION ALL
        SELECT BSM, DATE, HOUR, M_ATT, AVG_HLD FROM t4 WHERE    ".$whereCondition."
        ) s
    GROUP BY BSM, DATE, HOUR ";

如何将Query-1和Query-2结合起来，如...

 SELECT     
        BSM, DATE, HOUR, SUM(s.ATT), SUM(s.AVG_HLD), SUM(s.M_ATT), SUM(s.M_AVG_HLD)
    FROM (
        ** Whatever it is **
        ) 
    GROUP BY BSM, DATE, HOUR ";

Answer 1

在所有4个子查询中生成UNION，为来自另一对表的列插入0列。

SELECT BSM, DATE, HOUR, SUM(ATT) AS ATT, SUM(AVG_HLD) AS AVG_HLD, SUM(M_ATT) AS M_ATT, SUM(M_AVG_HLD) AS M_AVG_HLD
FROM (
        SELECT BSM, DATE, HOUR, ATT, AVG_HLD, 0 AS M_ATT, 0 AS M_AVG_HLD FROM t1 WHERE  ".$whereCondition." 
        UNION ALL
        SELECT BSM, DATE, HOUR, ATT, AVG_HLD, 0 AS M_ATT, 0 AS M_AVG_HLD FROM t2 WHERE  ".$whereCondition." 
        UNION ALL
        SELECT BSM, DATE, HOUR, 0 AS ATT, 0 AS AVG_HLD, M_ATT, M_AVG_HLD FROM t3 WHERE    ".$whereCondition." 
        UNION ALL
        SELECT BSM, DATE, HOUR, 0 AS ATT, 0 AS AVG_HLD, M_ATT, M_AVG_HLD FROM t4 WHERE    ".$whereCondition."
    ) u
GROUP BY BSM, DATE, HOUR

Answer 2

你也可以这样试试

SELECT bsm, date, hour, 
       SUM(CASE WHEN src = 1 THEN att END) att, 
       SUM(CASE WHEN src = 1 THEN att_hld END) att_hld, 
       SUM(CASE WHEN src = 2 THEN att END) m_att, 
       SUM(CASE WHEN src = 2 THEN att_hld END) m_att_hld
FROM 
(
    SELECT 1 src, bsm, date, hour, att, avg_hld FROM t1 WHERE  ".$whereCondition." UNION ALL
    SELECT 1 src, bsm, date, hour, att, avg_hld FROM t2 WHERE  ".$whereCondition." UNION ALL
    SELECT 2 src, bsm, date, hour, m_att, avg_hld FROM t3 WHERE ".$whereCondition." UNION ALL
    SELECT 2 src, bsm, date, hour, m_att, avg_hld FROM t4 WHERE ".$whereCondition."
) t
 GROUP BY bsm, date, hour;

mysql查询从两组不同的表中选择两列

2 个答案: