Example官方介绍 Query by Example (QBE) is a user-friendly querying technique with a simple interface. It allows dynamic query creation and does not require to write queries containing field names. In fact, Query by Example does not require to write queri
一.无匹配器的情况: Person person = new Person(); person.setName("test"); Role role = new Role(); role.setName("经理"); person.setRole(role); ... Example<Person> ex = Example.of(person); //动态查询 personRepository.findAll(ex); personRepository
IN为什么慢? 在应用程序中使用子查询后,SQL语句的查询性能变得非常糟糕.例如: SELECT driver_id FROM driver where driver_id in (SELECT driver_id FROM driver where _create_date > '2016-07-25 00:00:00'); 独立子查询返回了符合条件的driver_id,这个问题是解决了,但是所用的时间需要6秒,可以通过EXPLAIN查看SQL语句的执行计划: 可以看到上面的SQL语句变成了相
一.基础实体 @MappedSuperclass public abstract class AbsIdEntity implements Serializable { private static final long serialVersionUID = 7988377299341530426L; public final static int IS_DELETE_YES = 1;// 标记删除 public final static int IS_DELETE_NO = 0;// 未删除,