mybatis动态sql使用bind绑定

1、bind绑定可以将ognl表达式的值绑定到一个变量中，方便后来引用这个变量的值。<bind name="_empName" value="'%' + empName +'%'"/>

2、假如我们想要模糊查询员工姓名：<select id="getEmpsByConditionChoose" resultMap="MyEmpByStep" databaseId="mysql"> select * from tbl_emp <where> <if test="empId!=null"> emp_id = #{empId} </if> <if test="empName!=null"> and emp_name like #{_empName} </if> </where> </select>

3、编写单元测试代码：@Test public void test1() throws Exception { String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); SqlSession sqlSession = sqlSessionFactory.openSession(); try { EmployeeMapper employeeMapper = sqlSession.getMapper(EmployeeMapper.class); Employee employee = new Employee(); employee.setEmpId(1); employee.setEmpName("%曹%"); List<Employee> employees = employeeMapper.getEmpsByConditionChoose(employee); System.out.println(employees); }finally { sqlSession.close(); } }

4、假如我们想要这个百分号不要写在代码，而是想写在sql语句中，可以使用bind标签进行绑定<select id="getEmpsByConditionChoose" resultMap="MyEmpByStep" databaseId="mysql"> select * from tbl_emp <bind name="_empName" value="'%' + empName +'%'"/> <where> <if test="empId!=null"> emp_id = #{empId} </if> <if test="empName!=null"> and emp_name like #{_empName} </if> </where> </select>

5、运行单元测试方法，查看后台打印的sql语句。

6、模糊溽朽孑臾查询我们推荐使用在代码中使用%传值。public void test1() throws Excepti泠贾高框on { String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); SqlSession sqlSession = sqlSessionFactory.openSession(); try { EmployeeMapper employeeMapper = sqlSession.getMapper(EmployeeMapper.class); Employee employee = new Employee(); employee.setEmpId(1); employee.setEmpName("%曹%"); List<Employee> employees = employeeMapper.getEmpsByConditionChoose(employee); System.out.println(employees); }finally { sqlSession.close(); } }