Question

我有以下表格：

        industries
        -----------
        + id
        + name

        users
        -----------
        + id
        + name

        teams
        -----------
        + id
        + name
        + type

        user_to_team
        -----------
        + id
        + user_id
        + team_id
        + industry_id

我正在运行以下sql查询：

        SELECT teams.id
        FROM teams 
        LEFT JOIN user_to_team ON user_to_team.`team_id` = teams.id 
        WHERE teams.type = 'general' 
        AND (user_to_team.industry_id NOT IN(1))
        GROUP BY user_to_team.team_id 
        LIMIT 1

问题是它返回user_to_team表中包含industry_id为1的团队。

Answer 1

您是否尝试在“ON”子句之后将该条件检查移至该表的“LEFT JOIN”语句中？

SELECT teams.id
FROM teams
LEFT JOIN user_to_team ON user_to_team.`team_id` = teams.id
AND user_to_team.industry_id NOT IN(1)
WHERE teams.type = 'general'
LIMIT 1

此外，您是否拥有该列的正确数据类型？

Answer 2

这假设任何给定的团队都可以与user_to_team表中的多个行业相关联。

SELECT DISTINCT teams.team_id
FROM teams
LEFT JOIN user_to_team
  ON user_to_team.team_id = teams.team_id
    AND user_to_team.industry_id = 1
WHERE teams.type = 'general'
  AND user_to_team.team_id IS NULL;

Answer 3

您可以使用LEFT JOIN / IS NULL

SELECT teams.id
FROM teams 
  LEFT JOIN user_to_team 
    ON  user_to_team.team_id = teams.id
    AND user_to_team.industry_id IN (1)    -- caution: this is IN
                                           -- and **not** NOT IN
WHERE teams.type = 'general' 
  AND user_to_team IS NULL ;

或NOT EXISTS子查询，更易于阅读：

SELECT teams.id
FROM teams 
WHERE teams.type = 'general' 
  AND NOT EXISTS
      ( SELECT *
        FROM user_to_team 
        WHERE user_to_team.team_id = teams.id 
          AND user_to_team.industry_id IN (1)       -- caution: this is IN 
                                                    -- and **not** NOT IN
      ) ;

SQL NOT IN运算符无法正常工作

3 个答案: