如何为命名查询设置参数 [英] How to set parameters for a Named Query

问题描述

你好我有一个命名查询

  @NamedQuery（name =StudyplanCategory.findByStatusAndLimit，
 query = SELECT s FROM StudyplanCategory s WHERE 
 s.status =：status LIMIT s.start =：start，s.end = end）
  

我想设置这样的限制：

  @NamedQuery（name = StudyplanCategory.findByStatusAndLimit，
 query =SELECT s FROM StudyplanCategory s WHERE 
 s.status =：status LIMIT s.start =：start，s.end = end）
  

但是这在服务器启动时显示错误。
我使用下面的代码来调用DAO类中的查询：

$ p $ Query query = entityManager.createNamedQuery（ StudyplanCategory.findByStatusAndLimit）;
int end =（start * pageNumber）;
query.setParameter（status，status）;
query.setParameter（start，start）;
query.setParameter（end，end）;
return（List< StudyplanCategory>）query.getResultList（）;


开始和结束参数需要设置。请帮助。

解决方案

由于@DataNucleus表示，LIMIT不是JPQL中的有效关键字。这不是指定要返回多少行的方式。这是你怎么做的：

  @NamedQuery（name =StudyplanCategory.findByStatusAndLimit，
 query =SELECT s FROM StudyplanCategory s WHERE 
 s.status =：status）
  

这会是调用命名查询的代码：

  Query query = entityManager.createNamedQuery（StudyplanCategory.findByStatusAndLimit）; 
 int end =（start * pageNumber）; 
 query.setParameter（status，status）; 
 query.setFirstResult（start）; 
 query.setMaxResults（end  -  start）; 
 return（List< StudyplanCategory>）query.getResultList（）; 
  

Hi I have a Named Query

@NamedQuery(name = "StudyplanCategory.findByStatusAndLimit",
            query = "SELECT s FROM StudyplanCategory s WHERE 
            s.status =:status LIMIT s.start=:start,s.end=end")

I want to set the limit like this:

@NamedQuery(name = "StudyplanCategory.findByStatusAndLimit", 
            query = "SELECT s FROM StudyplanCategory s WHERE 
            s.status =:status LIMIT s.start=:start,s.end=end")

But this is showing error at the start up of the Server. I am using the below code to call the query in the DAO class:

Query query = entityManager.createNamedQuery("StudyplanCategory.findByStatusAndLimit");
int end=(start*pageNumber);
query.setParameter("status", status);
query.setParameter("start", start);
query.setParameter("end", end);
return (List<StudyplanCategory>) query.getResultList();

Start and End Parameters needs to be set. Please Help.

解决方案

As @DataNucleus said, LIMIT is not a valid keyword in JPQL. That's not the way to specify how many rows to return. This is how you do it:

@NamedQuery(name = "StudyplanCategory.findByStatusAndLimit", 
        query = "SELECT s FROM StudyplanCategory s WHERE 
                    s.status =:status")

And this would be the code to call the named query:

Query query = entityManager.createNamedQuery("StudyplanCategory.findByStatusAndLimit");
int end=(start*pageNumber);
query.setParameter("status", status);
query.setFirstResult(start);
query.setMaxResults(end - start);
return (List<StudyplanCategory>) query.getResultList();

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