Question

我试图从两个相同的表中选择得分和user_id（从表名中删除）

SELECT user_id, score as score
    FROM (
        SELECT tes.score FROM test_score tes INNER JOIN user U ON U.id = tes.user_id WHERE U.organization_id = 7
        UNION ALL
        SELECT tas.score FROM task_score tas INNER JOIN user U ON U.id = tas.user_id WHERE U.organization_id = 7
    ) AS subquery ORDER BY score DESC LIMIT 10

然而，当我运行这个时，我得到以下错误：

Error Code: 1054. Unknown column 'user_id' in 'field list'

表格如下：

Table: test_score
Columns:
id  int(11) PK AI
user_id int(11) 
module_id   int(11) 
score   double 
number_correct  int(11) 
correct_total   int(11) 
timestamp   datetime 
phase_id    int(11) 
medal_id    int(11) 
team_id int(11) 
status_id   int(11)

Answer 1

您的内部查询不会返回任何名为user_id的列，因此外部查询无法访问它。

请改为尝试：

SELECT user_id, score as score
    FROM (
        SELECT tes.user_id, tes.score FROM test_score tes INNER JOIN user U ON U.id = tes.user_id WHERE U.organization_id = 7
        UNION ALL
        SELECT tas.user_id, tas.score FROM task_score tas INNER JOIN user U ON U.id = tas.user_id WHERE U.organization_id = 7
    ) AS subquery ORDER BY score DESC LIMIT 10

Answer 2

您需要在两个SELECT语句中的子查询中选择user_id。

SELECT user_id, score as score
    FROM (
        SELECT tes.user_id, tes.score FROM test_score tes INNER JOIN user U ON U.id = tes.user_id WHERE U.organization_id = 7
        UNION ALL
        SELECT tas.user_id, tas.score FROM task_score tas INNER JOIN user U ON U.id = tas.user_id WHERE U.organization_id = 7
    ) AS subquery ORDER BY score DESC LIMIT 10

SQL联合选择多个列

2 个答案: