在此查询中，我收到错误

Question

在这个查询中：

String sql="select  BookCategory category from LibraryBook,BookMaster,BookCategory where (LibraryBook.id="+bookid+" AND LibraryBook.BookMaster.id=BookMaster.id AND BookMaster.BookCategory.id=BookCategory.id)";

我收到错误：

意外标记：第 1 行附近的类别，第 22 列 [从 com.xtr.schoolmanager.domain.facility.library.LibraryBook ,com.xtr.schoolmanager.domain.facility.library.BookMaster,com.xtr 中选择 BookCategory 类别。 schoolmanager.domain.facility.library.BookCategory where (LibraryBook.id=18 AND LibraryBook.BookMaster.id=BookMaster.id AND BookMaster.BookCategory.id=BookCategory.id)];嵌套异常是 org.hibernate.hql.internal.ast.QuerySyntaxException：意外令牌：第 1 行附近的类别，第 22 列 [从 com.xtr.schoolmanager.domain.facility.library.LibraryBook 中选择 BookCategory 类别，com.xtr.schoolmanager。 domain.facility.library.BookMaster,com.xtr.schoolmanager.domain.facility.library.BookCategory where (LibraryBook.id=18 AND LibraryBook.BookMaster.id=BookMaster.id AND BookMaster.BookCategory.id=BookCategory.id)]

请帮助我得到一个正确的答案。

Answer 1

这就是问题所在：

select  BookCategory category

我猜你想从BookCategory 表中选择category 列？在这种情况下，它应该是：

select  BookCategory.category