我如何计算这个 mysql UNION 查询

Question

这是我的查询，我仍然有点掌握 mysql 连接的窍门。我想获得此查询的计数....

SELECT *
FROM `users`
WHERE id = '4'
UNION
SELECT *
FROM `users`
WHERE id IN 
(SELECT group_id 
FROM `users` 
WHERE id = '4')
AND status = '1'

Answer 1

可以算子查询

  select count(*) from (

  SELECT *
  FROM `users`
  WHERE id = '4'
  UNION
  SELECT *
  FROM `users`
  WHERE id IN 
  (SELECT level 
  FROM `users` 
  WHERE id = '4')
  AND status = '1') t

Answer 2

我同意 scaisEdge 关于要使用的代码。但是，你想在子查询中做什么？这似乎是在寻找 ID，但是您为 IN 语句选择了 'Level'？除非LEVEL与ID相同，否则它不会做任何事情。

SELECT *
FROM `users`
WHERE id IN 
(SELECT level 
FROM `users` 
WHERE id = '4')
AND status = '1'

我如何计算这个 mysql UNION 查询

How do i count this mysql UNION query

mysql

union-all