MyBatis动态SQL foreach标签实现批量插入

需求:查出给定id的记录:

<select id="getEmpsByConditionForeach" resultType="com.test.beans.Employee">        SELECT * FROM tb1_emplyee WHERE id IN        <foreach collection="list" item="item_id" separator="," open="(" close=")">            #{item_id}        </foreach></select>

关于foreach标签,有几个属性应该注意一下:

        collection：指定要遍历的集合：        list类型的参数会特殊处理封装在map中，map的key就叫list        item：将当前遍历出的元素赋值给指定的变量        separator:每个元素之间的分隔符        open：遍历出所有结果拼接一个开始的字符        close:遍历出所有结果拼接一个结束的字符        index:索引。遍历list的时候是index就是索引，item就是当前值        遍历map的时候index表示的就是map的key，item就是map的值        #{变量名}就能取出变量的值也就是当前遍历出的元素

测试方法:

@Testpublic void testDynamicSqlTest() throws IOException{SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();//1、获取到的SqlSession不会自动提交数据SqlSession openSession = sqlSessionFactory.openSession();try{    EmployeeMapperDymanicSQL mapper=openSession.getMapper(EmployeeMapperDymanicSQL.class);/*Employee employee=new Employee(1,"lili",null,"1");*/List<Employee> emps=mapper.getEmpsByConditionForeach(Arrays.asList(1,2,3,4));    for (Employee e:emps){System.out.println(e);}}finally {openSession.close();}}

foreach标签也可以实现实现批量插入(删除)数据:

这里以批量插入数据为例:

<insert id="addEmps">        INSERT INTO tb1_emplyee(last_name,email,gender,d_id)        VALUES         <foreach collection="emps" item="emp" separator=",">            (#{emp.lastName},#{emp.email},#{emp.gender},#{emp.dept.id})        </foreach></insert>

对应的接口:

  public void addEmps(@Param("emps")List<Employee> emps);

测试方法

@Testpublic void testBatchSave() throws IOException{SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();//1、获取到的SqlSession不会自动提交数据SqlSession openSession = sqlSessionFactory.openSession();try{EmployeeMapperDymanicSQL mapper=openSession.getMapper(EmployeeMapperDymanicSQL.class);List<Employee> emps=new ArrayList<Employee>();emps.add(new Employee(null,"Eminem","[e-mail]","1",new Department(1)));emps.add(new Employee(null,"2Pac","[e-mail]","1",new Department(1)));mapper.addEmps(emps);openSession.commit();}finally {openSession.close();}}