Using MyBatis for range query operations

The specific code example of using MyBatis to implement the greater than or equal query operation is as follows:

Suppose we have a User entity class, which contains a # In the ##age field, we need to query the user data that age is greater than or equal to a certain value. First, we need to write a query statement in the Mapper.xml file.

<!-- 在Mapper.xml文件中编写查询语句 -->
<select id="selectUsersByAge" resultType="User">
    SELECT * FROM user
    WHERE age >= #{minAge}
</select>

Next, define a method in the

UserMapper interface to call the above query statement.

// UserMapper.java

import java.util.List;

public interface UserMapper {
    List<User> selectUsersByAge(int minAge);
}

Then, we map this method to the corresponding query statement in the

UserMapper.xml file.

<!-- 在UserMapper.xml文件中映射方法到查询语句 -->
<mapper namespace="com.example.mapper.UserMapper">
    <select id="selectUsersByAge" parameterType="int" resultType="User">
        SELECT * FROM user
        WHERE age >= #{minAge}
    </select>
</mapper>

Finally, call this method in the code to implement the greater than or equal query operation.

// 在代码中调用该方法来实现大于等于查询操作

public class UserService {

    private SqlSessionFactory sqlSessionFactory;

    public UserService(SqlSessionFactory sqlSessionFactory) {
        this.sqlSessionFactory = sqlSessionFactory;
    }

    public List<User> getUsersByMinAge(int minAge) {
        try(SqlSession session = sqlSessionFactory.openSession()) {
            UserMapper userMapper = session.getMapper(UserMapper.class);
            return userMapper.selectUsersByAge(minAge);
        }
    }
}

// 调用示例
SqlSessionFactory sqlSessionFactory = // 初始化SqlSessionFactory
UserService userService = new UserService(sqlSessionFactory);
List<User> users = userService.getUsersByMinAge(18);

Through the above code example, we can use MyBatis to perform a greater than or equal query operation.

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