Question

我正试图了解如何根据HAVING计算mysql行数。

SELECT COUNT(*),
  SUM(CASE WHEN sentby='$user_id' AND hiddenbysentby=0 THEN 1 ELSE 0 END) as sentbyuser,
  SUM(CASE WHEN sentto='$user_id' AND hiddenbysentto=0 THEN 1 ELSE 0 END) as senttouser
  FROM cb_users.user_pm
  WHERE title LIKE '%$search%'
  HAVING senttouser = 1 OR sentbyuser = 1

我要计算符合这些条件的行

SUM(CASE WHEN sentby='$user_id' AND hiddenbysentby=0 THEN 1 ELSE 0 END)

SUM(CASE WHEN sentto='$user_id' AND hiddenbysentto=0 THEN 1 ELSE 0 END)

我有第二个功能，可以不使用COUNT（*）显示此数据，并且可以正常工作。

但是此查询选择所有行，无论hiddenbysentby = 1或0 AND hiddenbysentto = 1还是0

Answer 1

您应该通过WHERE子句中的hiddenbysentby和hiddenbysentto字段移动条件，并通过用户ID添加条件

SELECT COUNT(*),
  SUM(CASE WHEN sentby='$user_id' THEN 1 ELSE 0 END) as sentbyuser,
  SUM(CASE WHEN sentto='$user_id' THEN 1 ELSE 0 END) as senttouser
  FROM cb_users.user_pm
  WHERE title LIKE '%$search%' AND (hiddenbysentby=0 AND sentby='$user_id') OR (hiddenbysentto=0 AND sentto='$user_id')
  HAVING senttouser = 1 OR sentbyuser = 1

Answer 2

您应将HAVING子句更改为：

具有已发送给用户> = 1或已由发送用户> = 1

在对行求和时，您的值将等于每个行的总行数，因此，除非只有正好符合条件的一行，否则您将找不到想要的结果

具有子句错误结果的SQL计数

2 个答案: