Question

我有不同的MySQL SELECT查询，都有不同的where语句。这些产生总数，唯一总数，某种类型的总数。

所以对于实例：

Loc    | total | unique | missing

London | 10 | 5 | 2

New York |20 |10 |5

目前我正在分别运行每个Select查询，但我宁愿一次运行它们。有没有办法在MySQL中做到这一点？

类似的东西：

SELECT
    Location
    Count(total)
    SELECT 
        count(unique)
    FROM
        .. my tables..
    WHERE
        .. where clause for unique part ..
    GROUP BY
        unique
FROM
    .. my tables ..
WHERE
    .. where clause for total part ..
GROUP BY
    total

Answer 1

也许你想要的是一个UNION

SELECT * from table where...
UNION
SELECT * from table where...

显然，每个查询返回的列必须相同。

Answer 2

我希望子查询（或几个）是有序的。

select location, (select count(total)  
                  from totalTable
                  where totalTable.location = locationTable.location) as total,
                 (select count(uniqe)
                  from uniqeTable
                  where uniqeTable.location = locationTable.location) as uniqe,
                 (select count(missing)
                  from missingTable
                  where missingTable.location = locationTable.location) as missing
from locationTable
where locationCriteria = searchCriteria

如果需要，您可以在多个子查询中引用同一个表 - 只需尝试将它们连接到id上，最好是在正确索引的内容上。显然必须根据需要调整where子句。

Answer 3

谢谢大家。对于任何试图掌握这一点的人来说，我的最终解决方案是：

SELECT
   Geo,
   total,
   SUM(unique) as unique
FROM
   (SELECT
      Geo,
      COUNT(total) AS total,
      0 unique,
    FROM
      -- my tables --
    WHERE
      -- where clause for totals --
    GROUP BY 
      Geo)
  UNION
    (SELECT
      Geo,
      0 total,
      COUNT(unique) AS unique,  
     FROM
       -- my tables --
     WHERE 
       -- where clause for unique --
     GROUP BY
       Geo)
) as tmptable
GROUP BY 
   Geo

MySQL：创建具有多个where子句的数据集

3 个答案: