Question

表'volcado'：id，reserva，cantidad

使用以下查询：

SELECT (CASE
         WHEN sum(cantidad) > 0 THEN 1
         WHEN sum(cantidad) <= 0 THEN 0
       END) AS suma 
FROM volcado
GROUP BY reserva

结果是：

╔══════╗
║ suma ║
╠══════╣
║  1   ║
║  1   ║
║  0   ║
║  1   ║
║  0   ║
╚══════╝

我需要查询的结果是：3

如何在同一个查询中SUM（）'suma'的行？

我不知道它运行：

SELECT SUM(SELECT (CASE
        WHEN sum(cantidad) > 0 THEN 1
        WHEN sum(cantidad) <= 0 THEN 0
      END) AS suma FROM volcado GROUP BY reserva)
FROM volcado

错误：

子查询返回超过1行

提前致谢。

Answer 1

试试这种方式

SELECT SUM(a.suma) from 
    (SELECT (CASE
        WHEN sum(cantidad) > 0 THEN 1
        WHEN sum(cantidad) <= 0 THEN 0
        END) AS suma FROM volcado GROUP BY reserva)a

Answer 2

这应该有效，将子查询用作表而不是列。

SELECT SUM(suma) from 
    (SELECT (CASE
        WHEN sum(cantidad) > 0 THEN 1
        WHEN sum(cantidad) <= 0 THEN 0
        END) AS suma FROM volcado GROUP BY reserva)

Answer 3

您可以使用CTE：

;WITH cte AS
  (SELECT CASE
              WHEN sum(cantidad) > 0 THEN 1
              WHEN sum(cantidad) <= 0 THEN 0
          END suma
   FROM volcado
   GROUP BY reserva)
SELECT sum(suma)
FROM cte

Answer 4

如果您愿意，可以简化查询。因此，不要使用case使用having：

SELECT COUNT(*)
FROM (SELECT reserva
      FROM volcado
      GROUP BY reserva
      HAVING SUM(cantidad) > 0
     ) r;

SUM（）GROUP BY列的结果

4 个答案: