JPA跟mybitis比较，简单的业务搜索是方便的，但是设计到复杂的SQL搜索时，我们需要自定义SQL。
1.@Query直接写SQL,缺点是无法动态的组装条件
2.JPA的Specification对象动态组装where搜索条件
3.entityManager执行CriteriaBuilder
4.entityManger直接使用createNativeQuery，执行原生SQL。这里设计到返回结果集的承载体必须是数据库对应的实体。
这里说一个自定义的VO承接返回结果集的方法。
ProjectAttendanceEntity
@Id@GeneratedValue(strategy = GenerationType.IDENTITY)private Long id;@Column(name = "f_id")private Long fId;@Column(name = "user_id")private Integer userId;@Column(name = "zh_name")private String zhName;@Column(name = "po_code")private String poCode;@Column(name = "po_name")private String poName;@Column(name = "punch_date")private String punchDate;@Column(name = "is_original")private String isOriginal;@Column(name = "attendance_hours")private String attendanceHours;@Column(name = "work_hours")private String workHours;@Column(name = "punch_area")private String punchArea;
结果集承接VO (AttendancePoSzVO)
private String poId;private String poName;private String zhName;
执行接口：
/*** 批量修改项目名称* @return*/@PostMapping("/po/sz/batch/{project}/{pn}/{ps}")public PageResultVO findBatchPoInfoByUserIdAndDate(@RequestBody List<Long> ids,@PathVariable String project,@PathVariable Integer pn,@PathVariable Integer ps){log.info("url:/po/sz/batch/"+"|param:"+ids);//通过id查询数据List<ProjectAttendanceEntity> projects = projectAttendanceEntityRepository.findByIdIn(ids);//获取SQLString sql = getSQL(projects,pn,ps);Query query = entityManager.createNativeQuery(sql);List<AttendancePoSzVO> list = query.unwrap(NativeQuery.class).setResultTransformer(Transformers.aliasToBean(AttendancePoSzVO.class)).getResultList();//初始化结果集List<DropDownVO> result = new ArrayList<>();for(AttendancePoSzVO poSz : list){result.add(new DropDownVO(poSz.getPoName(),poSz.getPoId()));}return new PageResultVO(GlobalReturnCode.SUCCESS_CODE,"SUCCESS",ps,pn,result);}/*** 组装查询SQL* @return*/public String getSQL(List<ProjectAttendanceEntity> poStatus, Integer pn, Integer ps){StringBuilder sql = new StringBuilder("SELECT DISTINCT res.po_id as poId,res.po_name as poName, GROUP_CONCAT(DISTINCT res.user_id) AS zhName ");sql.append(" FROM (");sql.append(" SELECT tt.po_name,tt.po_id,tt.user_id");sql.append(" FROM sie_sz_po_attendance_v tt ");sql.append(" WHERE");for(ProjectAttendanceEntity po : poStatus){sql.append("(tt.user_id = ").append(po.getUserId()).append(" and tt.rt_begin_date <= '").append(po.getPunchDate()).append("' and tt.rt_end_date >= '").append(po.getPunchDate()).append("') OR ");}//截掉最后一个ORsql = new StringBuilder(sql.substring(0,sql.length()-3));sql.append(" ) res");sql.append(" GROUP BY res.po_name,res.po_id");sql.append(" HAVING ");for(ProjectAttendanceEntity po : poStatus){sql.append(" INSTR(zhName,").append(po.getUserId()).append(") >0").append(" AND ");}//截取最后一个ANDsql = new StringBuilder(sql.substring(0,sql.length()-4));sql.append(" LIMIT ").append(pn).append(",").append((pn+1)*ps);return sql.toString();}
核心代码：
List<AttendancePoSzVO> list = query.unwrap(NativeQuery.class).setResultTransformer(Transformers.aliasToBean(AttendancePoSzVO.class)).getResultList();
但是这里的 setResultTransformer 已经过时了。
所以接下来寻找 setResultTransformer的替代API。
