博客

|一、if

1、在UserMapper.xml中编写if条件（where:可以去掉多余的字符）

<!--查询多种条件  -->
  <select id="selectAll" parameterType="map" resultType="com.createblue.bean.User">
  	select * from user 
  	<where>
  		<if test="userName != null and userName !=''">
  			and user_name = #{userName}
  		</if>
  		<if test="userSex != null and userSex !=''">
  			and user_sex = #{userSex}
  		</if>
  	</where>
  </select>

2、在UserMapper.java接口中引用方法

//多种条件查询
	List<User> selectAll(Map<String, Object> map);

3、在controller调用

@RequestMapping("selectAll")
	public void selectAll(@RequestParam Map<String, Object> map) {
		List<User> selectAll = um.selectAll(map);
		System.out.println(selectAll);
	}

url地址访问:

二、foreach循环

1、在xml写del语句

<!-- 批量删除 -->
  <delete id="dels" parameterType="List" >
  	delete from user where user_id in
  	<foreach collection="array" open="(" close=")" separator="," item="id">
  		#{id}
  	</foreach>
  </delete>

2、在同名的.java接口中调用del语句

//批量删除
	int dels(Integer[] userId);

3、在controller层调用并执行

@RequestMapping("dels")
	public void dels(Integer[] userId) {
		int dels = um.dels(userId);
		System.out.println(dels);
	}

url访问地址:



三、自定义字段名称

1、使用resultMap(结果集映射)

<!--自定义字段关联  -->
<resultMap type="com.createblue.bean.User" id="a">
 	<id column="user_id" property="userId"/>
 	<result column="user_name" property="userName"/>
 	<result column="user_sex" property="userSex"/>
 	<result column="user_password" property="userPwd"/>
 </resultMap>
 
  <!--查询  -->
  <select id="queryAll" parameterType="map"
          resultMap="a">
      select * from user 
  </select>