在JPA条件API中使用NOT EXISTS构建查询 [英] Building a query using NOT EXISTS in jpa criteria api

问题描述

我有两个名为table1，table2的表.两个表都没有相同的字段.这两个表之间没有关系.我的要求是我想要table1中所有不在table2中的记录.因此，我已经使用Criteria API编写了查询.但这并没有给出正确的结果.由于我是这个JPA和标准API的新手，任何人都可以指出我做错的地方.下面是我用来执行此操作的代码.

I have two tables named as table1 ,table2.Both the tables are having same no of fields.There is no relation between these two tables.My requirement is I want all the records in table1 which are not there in table2. So I have written a query using Criteria API. But it is not giving the correct result. As I am new to this JPA and criteria API, can any one point me where I am doing wrong.The below code I am using to do this.

CriteriaBuilder cb = mediationEntityManager.getCriteriaBuilder();
CriteriaQuery<Table1>  cq = cb.createQuery(Table1.class);
Root<Table1> table1 = cq.from(Table1.class);
cq.select(table1)

Subquery<Table2> subquery =  cq.subquery(Table2.class)
Root table2 = subquery.from(Table2.class)
subquery.select(table2)
cq.where(cb.not(cb.exists(subquery)))
TypedQuery<Table1> typedQuery = mediationEntityManager.createQuery(cq); 
List<Table1> resultList = typedQuery.getResultList();

MySQL查询:

SELECT table1 
FROM   table1 table1 
WHERE  NOT EXISTS (SELECT table2 
                   FROM   table2 table2 
                   WHERE  table2.name = table1.name 
                          AND table2.education = table1.education 
                          AND table2.age = table1.age) 
       AND table1.name = 'san' 
       AND table1.age = '10'; 

对于上述MySQL查询，我需要JPA标准API查询.

I need the JPA criteria API query for the above mentioned MySQL query.

推荐答案

您可以使用Criteria API尝试以下代码.我没有尝试过，但是您可以尝试相应地修改代码.

You can try the below code with Criteria API. I haven't tried, but you can try modifying the code accordingly.

CriteriaBuilder cb = mediationEntityManager.getCriteriaBuilder();  
CriteriaQuery<Table1> query = cb.createQuery(Table1.class); 
Root<Table1> table1 =  query.from(Table1.class); 
query.select(table1);
//--  
Subquery<Table2> subquery = query.subquery(Table2.class); 
Root<Table2> table2 = subquery.from(Table2.class);  
subquery.select(table2);  
//--
List<Predicate> subQueryPredicates = new ArrayList<Predicate>(); 
subQueryPredicates.add(cb.equal(table1.get(Table1_.name), table2.get(Table2_.name)));
subQueryPredicates.add(cb.equal(table1.get(Table1_.age), table2.get(Table2_.age)));
subQueryPredicates.add(cb.equal(table1.get(Table1_.education), table2.get(Table2_.education)));
subquery.where(subQueryPredicates.toArray(new Predicate[]{})); 
//--
List<Predicate> mainQueryPredicates = new ArrayList<Predicate>(); 
mainQueryPredicates.add(cb.equal(table1.get(Table1_.name), "san");
mainQueryPredicates.add(cb.equal(table1.get(Table1_.age), "10");
mainQueryPredicates.add(cb.not(cb.exists(subquery))); 
//--
query.where(mainQueryPredicates.toArray(new Predicate[]{})); 
TypedQuery<Table1> typedQuery =  mediationEntityManager.createQuery(query); 
List<Table1> resultList = typedQuery.getResultList();

此外，您还可以尝试下面的JPQL查询，该查询更易于理解，更改和修改.调试.

Also, you can try below JPQL query, which is easier to understand, alter & debug.

SELECT t1 
FROM   table1 t1, 
       table2 t2 
WHERE  t1.name = 'san' 
       AND t1.age = '10' 
       AND (t2.name <> t1.name 
             AND t2.education <> t1.education 
             AND t2.age <> t1.age); 

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