使用方法
1private Long usersSize; 2 3 @Formula("(id * 8888888)") 4 @JsonProperty 5 public Long getUsersSize(){ 6 return usersSize; 7 } 8 9 10 public void setUsersSize(Long usersSize) { 11 this.usersSize = usersSize; 12 } 13略。。。。
注意 必须使用（）来包裹sql片段，hibernate不会在数据库创建userSize对应的列
查看下生成的hibernate 生成的 sql，很明显是在数据库做了运算
1select agent0_.id as id1_, agent0_.acl_code as acl2_1_, agent0_.acl_type as acl3_1_, agent0_.created_by 2as created4_1_, agent0_.created_dt as created5_1_, agent0_.updated_by as updated6_1_, agent0_.updated_dt 3as updated7_1_, agent0_.version as version1_, agent0_.agent_addres as agent9_1_, agent0_.agent_city 4as agent10_1_, agent0_.agent_county as agent11_1_, agent0_.agent_name as agent12_1_, agent0_.agent_province 5as agent13_1_, agent0_.agent_scale as agent14_1_, agent0_.zip_code as zip15_1_, agent0_.biz_lic_reg_no 6as biz16_1_, agent0_.join_date as join17_1_, agent0_.oper_org_type as oper18_1_, agent0_.org_code_cert_no 7as org19_1_, (agent0_.id * 8888888) as formula0_ from agent_agent agent0_ order by agent0_.created_dt 8desc limit 15
甚至你可以这样玩：
查询该代理下用户总数
@Formula("(select count(*) from tbl_auth_user o where o.agent_id = id)")
id 代表当前表的id
1@Formula("(select count(*) from tbl_auth_user o where o.agent_id = id)") 2 @JsonProperty 3 public Long getUsersSize(){ 4 return usersSize; 5 }
hibernate生成的 sql
1select agent0_.id as id1_, agent0_.acl_code as acl2_1_, agent0_.acl_type as acl3_1_, agent0_.created_by 2as created4_1_, agent0_.created_dt as created5_1_, agent0_.updated_by as updated6_1_, agent0_.updated_dt 3as updated7_1_, agent0_.version as version1_, agent0_.agent_addres as agent9_1_, agent0_.agent_city 4as agent10_1_, agent0_.agent_county as agent11_1_, agent0_.agent_name as agent12_1_, agent0_.agent_province 5as agent13_1_, agent0_.agent_scale as agent14_1_, agent0_.zip_code as zip15_1_, agent0_.biz_lic_reg_no 6as biz16_1_, agent0_.join_date as join17_1_, agent0_.oper_org_type as oper18_1_, agent0_.org_code_cert_no 7as org19_1_, (select count(*) from tbl_auth_user o where o.agent_id = agent0_.id) as formula0_ 8from agent_agent agent0_ order by agent0_.created_dt desc limit 15
更多用例
1@Formula("(select min(o.creation_date) from Orders o where o.customer_id = id)") 2private Date firstOrderDate; 3 4@Formula("(select max(o.creation_date) from Orders o where o.customer_id = id)") 5private Date lastOrderDate; 6 7@Formula("(select coalesce(extract ('day' from age(max(o.creation_date))), 9999) from Orders o where o.customer_id = id)") 8private int daysSinceLastOrder;
@Formula （公式）虽好，但是不要滥用哦