在postgres中合併多個查詢

Question

我有2個查詢。 查詢1： -

select mr.id,count(ml.id) as labor_cnt 
from mreq Mr 
join mlbr ml on Mr.id = ml.mrid 
where Mr.id in(1235,3355) 
group by Mr.id 

查詢2： -

select mr.id,count(mm.id) as mtrial_cnt 
from mreq Mr join mmrm mm on Mr.id = mm.mrid 
where Mr.id in(1235,3355) 
group by Mr.id 

嘗試使用UNION ALL，但將無法正常工作。建議任何替代方法來合併它們。

Answer 1

既然你在這兩個查詢mr.id分組，我假設你想要的結果是這樣的：

mr.id | labor_cnt | mtrial_cnt 
-------------------------------- 
    1 |   5 |   3 
    2 |  null |   6 
    3 |   4 |   2 
    4 |   3 |  null 
... 

如果這就是你要找的內容，那麼你就可以結合使用公用表表達式查詢。喜歡的東西：

WITH labor as (
    SELECT mr.id AS mrid, count(ml.id) AS labor_cnt 
    FROM mreq mr JOIN mlbr ml ON mr.id = ml.mrid 
    WHERE mr.id IN (1235, 3355) 
    GROUP BY mr.id), 

mtrial as (
    SELECT mr.id AS mrid, count(mm.id) AS mtrial_cnt 
    FROM mreq mr JOIN mmrm mm ON mr.id = mm.mrid 
    WHERE mr.id in (1235, 3355) 
    GROUP BY mr.id) 

SELECT COALESCE(l.mrid, m.mrid), l.labor_cnt, m.labor_cnt 
    FROM labor l FULL OUTER JOIN mtrial m ON mrid 
ORDER BY mrid; 

編輯補充

它看起來像你使用MySQL，以及MySQL不支持公共表表達式。 MySQL支持子查詢，所以這可能會起作用（注意：我沒有驗證語法，因爲我沒有可用的MySQL實例）：

SELECT COALESCE(l.mrid, m.mrid), l.labor_cnt, m.labor_cnt 
    FROM 
    (SELECT mr.id AS mrid, count(ml.id) AS labor_cnt 
     FROM mreq mr JOIN mlbr ml ON mr.id = ml.mrid 
     WHERE mr.id IN (1235, 3355) 
    GROUP BY mr.id) AS labor 

    FULL OUTER JOIN 

    (SELECT mr.id AS mrid, count(mm.id) AS mtrial_cnt 
     FROM mreq mr JOIN mmrm mm ON mr.id = mm.mrid 
     WHERE mr.id in (1235, 3355) 
    GROUP BY mr.id) AS mtrial 

    ON mrid 

ORDER BY mrid;