最近开发遇到的一些查询用例，简单记录下

一、定义Repository
@Repository
public interface TransTaskManager extends JpaRepository<TransTask, Long>, JpaSpecificationExecutor<TransTask> {}

二、Repository查询语句

1，对象作为参数传输
@Modifying
@Transactional
@Query("update TransTask t set t.flowStatus =:#{#transTask.flowStatus} where t.flowStatus =:#{#oldStatus}")
int updateFlowStatus(@Param("transTask") TransTask transTask, @Param("oldStatus") int oldStatus);

2，字符串作为参数：
@Modifying
@Transactional
@Query("update TransTask t set t.transId =:transId where t.taskId =:taskId")
int updateTransId(@Param("transId") String transId, @Param("taskId") String taskId);

3，参数定位
@Query(" from TransTask t where t.taskId = ?1 and t.taskName like ?2 and t.flowStatus=100 and t.isDelete=2 ")
Page<TransTask> queryByParams(@Param("taskId") String taskId, @Param("taskName") String taskName, Pageable pageable);

4，原生sql
@Query(value = "select t.playUrl from ty_trans_task t where t.taskId =:taskId", nativeQuery = true)
String getPlayUrls(@Param("taskId") String taskId);

5，Example_实例查询
Person person = new Person();
person.setFirstname("Dave"); //Firstname = 'Dave'

ExampleMatcher matcher = ExampleMatcher.matching() .withMatcher("name", GenericPropertyMatchers.startsWith()) //姓名采用“开始匹配”的方式查询
.withIgnorePaths("int"); //忽略属性：是否关注。因为是基本类型，需要忽略掉

Example<Person> example = Example.of(person, matcher); //Example根据域对象和配置创建一个新的ExampleMatcher

6，specification查询

@Transactional(readOnly = true)
public Page<TransTaskRelExt> query(TransTaskReq req) {

PageRequest pageRequest = new PageRequest(req.getPageNum(), req.getPageSize(), Sort.Direction.valueOf(req.getOrder()), req.getSort());

Specification<TransTaskRelExt> specification = new Specification<TransTaskRelExt>() {
@Override
public Predicate toPredicate(Root<TransTaskRelExt> root, CriteriaQuery<?> query, CriteriaBuilder cb) {

                List<Predicate> predicates = new ArrayList<>();

            
                //任务编号
                if (StringUtils.isNotBlank(req.getTaskId())) {
                    predicates.add(cb.equal(root.get("taskId").as(String.class), req.getTaskId()));
                }

                //任务名称
                if (StringUtils.isNotBlank(req.getTaskName())) {
                    predicates.add(cb.like(root.get("taskName").as(String.class), "%" + req.getTaskName() + "%"));
                }

        // in 第一种写法
        Expression<String> exp = root.<String>get("id");//root.get("id").as(String.class)
                predicates.add(exp.in(noticeIds));
                
        // in 第二种写法
        CriteriaBuilder.In<Object> in = cb.in(root.get("id"));
        in.value("个人");
        in.value("企业");
        predicates.add(in);
                
        //in例子
                
        In<Long> in = cb.in(root.get(BailPay_.customerId));
        in.value(customer.id());
        predicates.add(in);
                     
                    
                    
        //or
        Predicate p = cb.equal(root.get("status").as(String.class), status);
        for (int i = 1; i < statuses.length; ++i) {
            p = cb.or(p, cb.equal(root.get("status").as(String.class), statuses[i]));
                }
        list.add(p);
                        
                        
        //or 例子
        Predicate p1=cb.like(root.get(“name”).as(String.class), “%”+uqm.getName()+“%”);
        Predicate p2=cb.equal(root.get("uuid").as(Integer.class), uqm.getUuid());
        Predicate p3=cb.gt(root.get("age").as(Integer.class), uqm.getAge());

        构建组合的Predicate示例：
        Predicate p = cb.and(p3,cb.or(p1,p2));
                    
                Predicate[] pre = new Predicate[predicates.size()];
                return query.where(predicates.toArray(pre)).getRestriction();
            }
        };

        return transTaskRelExtManager.findAll(specification, pageRequest);
    }