Hibernate QBC 简单收集

Hibernate QBC

介绍：

QBC（Query By Criteria）通过 API 来检索对象

主要由 Criteria 接口、Criterion 接口和 Exception 类组成，支持在运行时动态生成查询语句。

声明

事先定义：Department Employee 两个实体类

示例

查询

List<Employee> empList = session.createCriteria(Employee.class).list();

分页

List<Employee> empList = session.createCriteria(Employee.class).setFirestResult(0).setMaxResults(4).list();

Like 查询，忽略大小写

List<Employee> empList = session.createCriteria(Employee.class)
.add(Restrictions.like("ename","a",MatchMode.ANYWHERE).ignoreCase())
.list();

between 查询

list<Employee> empList = session.createCriteria(Employee.class)
.add(Restrictions.between("hiredate",begindate,enddate))
.list();

in 查询

list<Employee> empList = session.createCriteria(Employee.class)
.add(Restrictions.in("id",new Integer[]{12,123}))
.list();

> 或 >=

list<Employee> empList = session.createCriteria(Employee.class).add(Restrictions.ge("id",123)).list();

多条件查询

list<Employee> empList = session.createCriteria(Employee.class)
.add(Restrictions.ge("id",123))
.add(Restrictions.between("hiredate",begindate,enddate))
.add(Restrictions.like("ename","a", MatchMode.ANYWHERE).ignoreCase())
.list();

排序

list<Employee> empList = session.createCriteria(Employee.class)
.addOrder(Order.desc("salary"))
.list();

统计

list<Employee> empList = session.createCriteria(Employee.class)
.setProjection(Projections.rowCount())
.add(Restrictions.eq("dept.id",20))
.list();

count 统计

list<Employee> empList = session.createCriteria(Employee.class)
.setProjection(Projection.projectionList()
.add(Projetions.property("dept.id"))
.add(Projections.rowCount())
.add(Projections.avg("salary"))
.add(Projections.max("salary"))
.add(Projections.min("salary"))
.add(Projections.sum("salary"))
.add(Projections.groupProperty("dept.id")))
.list();

非空查询

list<Employee> empList = session.createCriteria(Employee.class).add(Restrictions.isNotNull("comm")).list();