Question

您好，我正在尝试从数据库部门实施查询（包含案例陈述），但我无法弄清楚问题出在哪里。

@Query("select new com.withgratitude.api.core.domain.ReportTopTenBiddersTable( CONCAT(u.firstName, ' ', u.lastName), " +
           "b.auctionId, b.date), " +
           " case when (b.isTheWinner = 0) then 'No' when (b.isTheWinner = 1) then 'Yes' else 'No Winner' end as winnerBid" +
           "                        from Bids b, Users u " +
           "                       where b.userId = u.userId " +
           "                       order by CONCAT(u.firstName, ' ', u.lastName)")
   List<ReportTopTenBiddersTable> reportTopTenBiddersTable();

Here is the Query I am trying to implement:
#top 10 bidders - table
select CONCAT(u.first_name, ' ', u.last_name) as name, b.auction_id, b.date, 
                              case b.is_thewinner when 0 then 'No' when 1 then 'Yes' end as WinnerBid, b.offer
                       from bids b, users u 
                       where b.user_id = u.user_id
                       order by name
                       limit 10;

Caused by: org.hibernate.hql.internal.ast.QuerySyntaxException: unexpected token: , near line 1, column 130 [select new com.withgratitude.api.core.domain.ReportTopTenBiddersTable( CONCAT(u.firstName, ' ', u.lastName), b.auctionId, b.date),  case when b.isTheWinner = 0 then 'No' when b.isTheWinner = 1 then 'Yes' else 'No Winner' end as winnerBid                        from com.withgratitude.api.core.dao.Bids b, com.withgratitude.api.core.dao.Users u                        where b.userId = u.userId                        order by CONCAT(u.firstName, ' ', u.lastName)]
at org.hibernate.hql.internal.ast.QuerySyntaxException.convert(QuerySyntaxException.java:74) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.hql.internal.ast.ErrorTracker.throwQueryException(ErrorTracker.java:93) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.parse(QueryTranslatorImpl.java:296) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:188) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:143) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:119) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:80) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:153) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.internal.AbstractSharedSessionContract.getQueryPlan(AbstractSharedSessionContract.java:595) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:704) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
... 83 common frames omitted

Answer 1

要添加到Andronicus答案中，我想您可以使用nativeQuery并以纯SQL编写数据库请求。

@Query(value = "select CONCAT(u.first_name, ' ', u.last_name) as name, b.auction_id, b.date, " +
        "case b.is_thewinner when 0 then 'No' when 1 then 'Yes' end as WinnerBid, b.offer " +
        "from bids b, users u " +
        "where b.user_id = u.user_id " +
        "order by name " +
        "limit 10", nativeQuery = true)
List<ReportTopTenBiddersTable> reportTopTenBiddersTable();

Answer 2

这里有很多问题-其中一个是返回类型（ReportTopTenBiddersTable对象的列表），它似乎没有地方保留完整的出价信息。

这些部分不合适（有sql和jpql混合使用），类型不对齐-但是很难从这个简短的示例中看出错误的根源-以及最佳解决方案。

最简单的解决方案之一是将出价信息添加到ReportTopTenBiddersTable对象；这样，您可以删除case（但仍保留数据）并保持签名不变：

更改构造函数ReportTopTenBiddersTable以接受“出价”对象（并将其存储在字段中）。
在查询开始时将构造函数调用更改为包含b（您可以省略日期，因为无论如何它都可以从b访问）：

  select new com.withgratitude.api.core.domain.ReportTopTenBiddersTable(
      CONCAT(u.firstName, ' ', u.lastName), b.auctionId, b.date) ...

当我尝试在JPQL中使用Case语句时出现问题

2 个答案: