Mysql添加连接子查询以计数

Question

我有两张表 Loan 和 Book。

通过这个查询，我通过计算 Book_ID 来计算从 Loan 中借出的书籍最多：

select Book_ID, count(Book_ID) as Count
from Loan
group by Book_ID
order by Count desc;

现在我想在此处从 Book 表中添加书名。我在 Loan 表中有 Book_ID 作为外键。我不太确定如何将这个查询放在一起。

这是我尝试过的，但没有结果：

select Book_ID, count(Book_ID) as Count, Book.Title
from Loan, Book
where Loan.Book_ID = Book.Book_ID
group by Book_ID
order by Count desc;

Answer 1

由于您已加入另一个表，因此您的列名不明确，请尝试给它们一个别名：

select Book.Book_ID, count(Book.Book_ID) as Count, Book.Title
from Loan, Book
where Loan.Book_ID = Book.Book_ID
group by Book.Book_ID
order by Count desc;