选择语句中的子查询返回SQL错误

Question

我收到此查询的SQL错误

错误号：1064
您的SQL语法有误； 检查与您的MySQL服务器版本相对应的手册以获取在'*附近使用的正确语法
来自`cast_gallery` q
在q.all_media_id = r.id上加入`all_media` r
第1行的q.pa'

SELECT `cast_name`, `cast_slug`, (SELECT count(q.*)
 FROM `cast_gallery` q
 JOIN `all_media` r on q.all_media_id=r.id
 WHERE q.parent = `casts`.`id` AND r.approved=1) as image_gallery, `active`, `view`, `checked`, `sex`, `id`
FROM (`casts`)
ORDER BY `cast_name` asc
LIMIT 10

怎么解决？

Answer 1

要计算总行数，我们使用COUNT(*) ，而不是Count(q.*) 。 另外，在From子句中不需要在casts周围加上括号。

SELECT `cast_name`, 
       `cast_slug`, 
       (SELECT count(*)
        FROM `cast_gallery` q
        JOIN `all_media` r on q.all_media_id=r.id
        WHERE q.parent = `casts`.`id` AND 
              r.approved=1) as image_gallery, 
      `active`, 
      `view`, 
      `checked`, 
      `sex`, 
      `id`
FROM `casts`
ORDER BY `cast_name` asc
LIMIT 10

附加信息：

COUNT(...)用于计算非NULL值的数量； 但是COUNT(*)将计算检索到的总行数，无论它们是否包含NULL值。

Answer 2

尝试仅将count(q.*)更改为count(*)

Answer 3

计数语法不正确。 如果要在子查询中查找行数，可以使用count（*）。 有关更多说明，请参阅http://www-db.deis.unibo.it/courses/TW/DOCS/w3schools/sql/sql_func_count.asp.html 。

SELECT `cast_name`, `cast_slug`, (SELECT count(*)
FROM `cast_gallery` q
JOIN `all_media` r on q.all_media_id=r.id
WHERE q.parent = `casts`.`id` AND r.approved=1) as image_gallery, `active`, 
`view`, `checked`, `sex`, `id`
FROM (`casts`)
ORDER BY `cast_name` asc
LIMIT 10

应该管用

Answer 4

您可以尝试使用q.all_media_id代替count（q。*）

SELECT `cast_name`, `cast_slug`, (SELECT count(q.all_media_id)
 FROM `cast_gallery` q
 JOIN `all_media` r on q.all_media_id=r.id
 WHERE q.parent = `casts`.`id` AND r.approved=1) as image_gallery, `active`, `view`, `checked`, `sex`, `id`
FROM (`casts`)
ORDER BY `cast_name` asc
LIMIT 10