mysql - SQL，合并同一个表的两个聚合

Question

我有下表，其中包含特定部门的operator在特定日期针对每个执行的操作数量>目标类型。 sum1 和 sum2 是特定日期操作 1 和操作 2 的数量，相关操作的解释由 operation_type 列指示.

statistic_id | department | operator | operation_type | target_type | sum1 | sum2 | date |

我将查询该表以收集按 operator 和 分组的特定时间段内 department 1 的 operation_type 1 统计信息>操作类型如下

SELECT operator, target_type, SUM(sum1) AS op1, SUM(sum2) AS op2 FROM statistics
WHERE
  department = 1 AND
  operation_type = 1 AND
  (date BETWEEN in_start_date AND in_end_date)
GROUP BY operator, target_type
ORDER BY operator, target_type;

此外，我还会查询表以收集同一部门和按相同条件分组的时间间隔的 operation_type 2 的统计信息

SELECT operator, target_type, SUM(sum1) AS op3, SUM(sum2) AS op4 FROM statistics
WHERE
  department = 1 AND
  operation_type = 2 AND
  (date BETWEEN in_start_date AND in_end_date)
GROUP BY operator, target_type
ORDER BY operator, target_type;

我想合并查询结果，这样我会得到像这样的结果

operator | target_type | op1 | op2 | op3 | op4

如何根据一些常见和不同的标准聚合不同的列，同时按同一组列进行分组，从而将表与自身连接起来？

Answer 1

在求和中使用条件聚合:

SELECT operator,
       target_type,
       SUM(CASE WHEN operation_type = 1 THEN sum1 ELSE 0 END) AS op1,
       SUM(CASE WHEN operation_type = 1 THEN sum2 ELSE 0 END) AS op2,
       SUM(CASE WHEN operation_type = 2 THEN sum1 ELSE 0 END) AS op3,
       SUM(CASE WHEN operation_type = 2 THEN sum2 ELSE 0 END) AS op4
FROM statistics
WHERE department = 1 AND
      date BETWEEN in_start_date AND in_end_date
GROUP BY operator, target_type
ORDER BY operator, target_type

这会对整个表进行一次遍历，并根据 operation_type 是 1 还是 2 有条件地获取您想要的总和。请注意，CASE 表达式仅包含 operation_type，而不包含部门或日期。这样做的原因是因为您最初的两个查询共享相同的 WHERE 条件，因此我们不需要移动它们。