#1241 - 操作数应包含 1 列嵌套查询

Question

我输入这个命令时发现这个错误

SELECT *
FROM  Borrowed_Book , User
WHERE User.UserId=Borrowed_Book.UserId  IN (
    SELECT *
    FROM Book , Book_version_info
    WHERE 
        Book_version_info.PublisherID = 1 AND 
        Book.ISBN= Book_version_info.Book_ISBN
);

我找不到这里的问题以及为什么会出现此错误我在网上查了也没找到原因

Answer 1

首先你应该在 IN 函数中匹配你的列：

WHERE User.UserId=Borrowed_Book.UserId  IN (
    SELECT *
    FROM Book , Book_version_info
    WHERE 
        Book_version_info.PublisherID = 1 AND 
        Book.ISBN= Book_version_info.Book_ISBN
);

SQL 不知道如何处理列应该相同，所以请尝试：

WHERE User.UserId=Borrowed_Book.UserId  AND User.UserId IN (
    SELECT User.UserId
    FROM Book , Book_version_info, User
    WHERE 
        Book_version_info.PublisherID = 1 AND 
        Book.ISBN= Book_version_info.Book_ISBN
);

#1241 - 操作数应包含 1 列嵌套查询

#1241 - Operand should contain 1 column(s) nested query

mysql

mysql-error-1241