Question

你好我在我的sql代码中计数count（返回= 0）时遇到了一些麻烦。

SELECT `return` 
FROM  `numbers`
WHERE list_id IN (
  SELECT id from listy where listy.number = "900000335300000939680320"
)

以下是一个示例，如何使用此确切查询对return = 0进行计数。

http://sqlfiddle.com/#!2/49501f/2

Answer 1

当然，您需要在查询中使用COUNT()，并添加AND以仅查看return = 0的行。

SELECT COUNT(`return` ) AS returncount
FROM  `numbers`
WHERE list_id IN (
  SELECT id from listy where listy.number = "900000335300000939680320"
) AND
`return` = 0

Answer 2

SELECT count(*) 
FROM  `numbers` 
WHERE list_id IN (SELECT id 
                  from listy 
                  where listy.number = "900000335300000939680320") 
                    AND `return` = 0;

Answer 3

您还可以将sum与表达式一起使用，它将被评估为布尔值，您可以根据您的条件计算，也可以使用连接而不是子查询，下面的查询将为您提供{{ 1}}和return=0

return=1

DEMO

Answer 4

在AND之后使用WHERE子句缩小结果（最后一行），而不是计算你有多少SELECT COUNT()：

SELECT COUNT(return)
FROM  numbers
WHERE list_id IN (
  SELECT id from listy where listy.number = "900000335300000939680320"
)
AND return = 0

Answer 5

这可能会对您有所帮助：

SELECT `return`,count(*) FROM  `numbers` n join `listy` l
on n.list_id = l.id
where l.number = "900000335300000939680320" 
and n.return = 0
group by `return`

sql fiddle

选择count where statement

5 个答案: