mysql - 使用嵌套选择 MySQL 语句的错误

Question

我目前正在尝试使用嵌套的选择语句，但我的子查询正在生成 NULL 值。我做错了什么？

SELECT filmid,datetime,title,description,
       (
          SELECT name 
          FROM fec_client 
          WHERE filmid = 'fec_film.filmid'
       ),
       (
          SELECT rating_motivation 
          FROM fec_rating_report 
          WHERE filmid = 'fec_film.filmid'
       ) 
FROM fec_film 
ORDER BY datetime DESC

Answer 1

删除引号，否则你不是在比较 SQL 中的值，而是在比较字符串

SELECT filmid, datetime, title, description, 
    ( SELECT name FROM fec_client WHERE filmid = fec_film.filmid ) AS name,
    ( SELECT rating_motivation FROM fec_rating_report WHERE filmid = fec_film.filmid ) AS rating   
FROM fec_film ORDER BY datetime DESC

附注您还可以使用“AS”关键字命名这些列