更新时间:2022-02-24 08:58:50
异常信息说:
图书未映射 [SELECT COUNT(*) FROM Books];嵌套异常是 org.hibernate.hql.ast.QuerySyntaxException:书籍未映射 [SELECT COUNT(*) FROM Books]
Books
未映射.也就是说,没有名为 Books
的映射类型.
Books
is not mapped. That is, that there is no mapped type called Books
.
事实上,没有.您的映射类型称为 Book
.它映射到名为Books
的表,但类型称为Book
.当您编写 HQL(或 JPQL)查询时,您使用类型的名称,而不是表.
And indeed, there isn't. Your mapped type is called Book
. It's mapped to a table called Books
, but the type is called Book
. When you write HQL (or JPQL) queries, you use the names of the types, not the tables.
因此,将您的查询更改为:
So, change your query to:
select count(*) from Book
虽然我认为可能需要
从Book b中选择count(b)
如果 HQL 不支持 *
符号.
If HQL doesn't support the *
notation.