JPQL BETWEEN用法详解与实例

在Java持久化查询语言（JPQL）中，BETWEEN关键字用于在WHERE子句中指定一个值的范围。通过使用BETWEEN，可以方便地筛选出符合特定范围条件的数据。本文将通过一个具体的实例，详细讲解如何使用JPQL的BETWEEN关键字。
实体类定义
首先，我们定义一个Employee实体类，用于表示员工信息：
java复制
@Entity
public class Employee {
@Id
@GeneratedValue
private long id;
private String name;
private Timestamp joinDate;
private long salary;
// 省略getter和setter方法
}
使用BETWEEN查询
接下来，我们将通过几个示例来展示如何使用BETWEEN关键字。
示例1：根据薪资范围查询员工
以下代码展示了如何查询薪资在2000到4000之间的员工：
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public static void findEmployeeBySalary() {
System.out.println(“-- Employee with salary BETWEEN 2000 and 4000 --”);
EntityManager em = entityManagerFactory.createEntityManager();
Query query = em.createQuery(
“SELECT e FROM Employee e WHERE e.salary BETWEEN 2000L AND 4000L order by e.salary”);
List resultList = query.getResultList();
resultList.forEach(System.out::println);
em.close();
}
运行结果：
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– Employee with salary BETWEEN 2000 and 4000 –
Employee{id=4, name=‘Mike’, joinDate=2015-08-19 19:00:00.0, salary=2000}
Employee{id=1, name=‘Diana’, joinDate=1999-11-14 18:00:00.0, salary=3000}
Employee{id=2, name=‘Rose’, joinDate=2011-04-30 19:00:00.0, salary=4000}
示例2：根据入职日期范围查询员工
以下代码展示了如何查询入职日期在1990-01-01到2010-05-01之间的员工：
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public static void findEmployeeByJoinDate() {
System.out.println(“-- Employee with join date BETWEEN ‘1990-01-01’ and ‘2010-05-01’ --”);
EntityManager em = entityManagerFactory.createEntityManager();
Query query = em.createQuery(
“SELECT e FROM Employee e WHERE e.joinDate BETWEEN ‘1990-01-01’ AND ‘2010-05-01’ order by e.joinDate”);
List resultList = query.getResultList();
resultList.forEach(System.out::println);
em.close();
}
运行结果：
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– Employee with join date BETWEEN ‘1990-01-01’ and ‘2010-05-01’ –
Employee{id=1, name=‘Diana’, joinDate=1999-11-14 18:00:00.0, salary=3000}
Employee{id=3, name=‘Denise’, joinDate=2006-01-09 18:00:00.0, salary=1500}
示例3：使用参数查询
在实际开发中，我们通常会使用参数化查询来提高代码的灵活性和安全性。以下代码展示了如何使用参数查询员工的入职日期范围：
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public static void findEmployeeByJoinDate2() {
System.out.println(“-- Employee with join date BETWEEN ‘2005-01-01’ and ‘2018-01-01’ --”);
EntityManager em = entityManagerFactory.createEntityManager();
Query query = em.createQuery(
“SELECT e FROM Employee e WHERE e.joinDate BETWEEN :startDate AND :endDate order by e.joinDate”);
query.setParameter(“startDate”, localToTimeStamp(LocalDate.of(2005,1,1)));
query.setParameter(“endDate”, localToTimeStamp(LocalDate.of(2018,1,1)));
List resultList = query.getResultList();
resultList.forEach(System.out::println);
em.close();
}
运行结果：
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– Employee with join date BETWEEN ‘2005-01-01’ and ‘2018-01-01’ –
Employee{id=3, name=‘Denise’, joinDate=2006-01-09 18:00:00.0, salary=1500}
Employee{id=2, name=‘Rose’, joinDate=2011-04-30 19:00:00.0, salary=4000}
Employee{id=4, name=‘Mike’, joinDate=2015-08-19 19:00:00.0, salary=2000}
示例4：使用NOT BETWEEN
NOT BETWEEN用于查询不在指定范围内的数据。以下代码展示了如何查询入职日期不在2005-01-01到2018-01-01之间的员工：
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public static void findEmployeeByJoinDate3() {
System.out.println(“-- Employee with join date NOT BETWEEN’2005-01-01’ and ‘2018-01-01’ --”);
EntityManager em = entityManagerFactory.createEntityManager();
Query query = em.createQuery(
“SELECT e FROM Employee e WHERE e.joinDate NOT BETWEEN :startDate AND :endDate order by e.joinDate”);
query.setParameter(“startDate”, localToTimeStamp(LocalDate.of(2005,1,1)));
query.setParameter(“endDate”, localToTimeStamp(LocalDate.of(2018,1,1)));
List resultList = query.getResultList();
resultList.forEach(System.out::println);
em.close();
}
运行结果：
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– Employee with join date NOT BETWEEN’2005-01-01’ and ‘2018-01-01’ –
Employee{id=1, name=‘Diana’, joinDate=1999-11-14 18:00:00.0, salary=3000}
总结
通过以上实例，我们可以看到JPQL的BETWEEN关键字非常强大，能够方便地实现范围查询。无论是数值范围还是日期范围，都可以通过BETWEEN关键字轻松实现。同时，结合参数化查询，还可以提高代码的灵活性和安全性。