mybatis 增删该查demo，新手必看

下面是一个完整的ｄｅｍｏ,userTemp和ｕｓｅｒ对象属性一样，这里就不写了

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> 
<mapper namespace="com.aring.dao.UserMapper"> 
      
    <resultMap type="com.aring.pojo.User" id="user">
        <result column="id" jdbcType="INTEGER" property="id"/>
        <result column="username" jdbcType="VARCHAR" property="userName"/>
        <result column="password" jdbcType="VARCHAR" property="passWord"/>
        <result column="age" jdbcType="INTEGER" property="age"/>  
        <result column="creat" jdbcType="TIMESTAMP" property="creat"/>     
    </resultMap>
    <resultMap type="com.aring.pojo.UserTemp" id="userTemp">
    </resultMap>
    <!-- 通过ｉｄ查询数据 --> 
    <select id="selectByPrimaryKey" resultMap="user" parameterType="java.lang.Integer">
        select * from user where id = #{id}
    </select>
     <!-- 插入数据操作 --> 
    <insert id="saveUser" parameterType="com.aring.pojo.User">
        insert into user (username,password,age,creat) values (#{userName},#{passWord},#{age},#{creat})
    </insert>
      <!-- 查询操作 -->
    <select id="userLogin" resultMap="user" parameterType="com.aring.pojo.User">
        select * from user where username=#{userName} and password=#{passWord}
    </select>
   <!-- 查询操作 -->
    <select id="findActiveBlogLike"  resultMap="userTemp">
  SELECT *  FROM user
  <where>
    <if test="id != null">
         id = #{id}
    </if>
    <if test="username != null">
        AND username like concat(concat('%',#{username}),'%')
    </if>
    <if test="age != null ">
        AND age = #{age}
    </if>
  </where>
</select>
   <!-- 查询分页操作 -->
     <select id="getAllUser" resultMap="user" >
        select * from user WHERE id= #{id} limit #{startPos},#{pageSize}
    </select>
   <!-- 更新操作 -->
    <update id="updateUser"  parameterType="com.aring.pojo.User">
        update user set  username=#{userName},password=#{passWord},age=#{age}
where id=#{id}
</update>
      <!-- 删除 --> 
    <delete id="deleteUser" parameterType="java.lang.Integer"> 
        delete from user WHERE id  = #{id} 
    </delete> 
       <!-- 查询操作 -->
    <select id="pagerUser" parameterType="java.util.Map" resultMap="user">
       select * from user where 1=1

       <if test="username!=null">
        and username like '%${username}%'
       </if>
        limit ${(index-1)*pageSize},${pageSize}
     </select>
        <!-- 查询总数量操作 -->
     <select id="countUser" parameterType="java.util.Map" resultType="int">
         select count(*) from user where 1=1
         <if test="username != null">
             and username like '%${username}%'   
         </if>
     </select>
   
</mapper>