Mybatis 各种标签使用

	@Data
	public class User{
	    private Long id;
	    private String name;
	}
	@Data
	public class Score{
	    private Long id;
	    private Integer score;
	    private Long subjectId;
	    private Long userId;
	}
	
	<resultMap id="userResult"    type="User">   </resultMap>
    <resultMap type="User" id="userExt">
        <result property="id" column="id"/>
        <result property="name" column="name"/>
		<collection property="scoreList" column="user_id" javaType="List" ofType="Score"  >
			<result property="userId" column="user_id"/>
			<result property="score" column="score"/>
			<result property="subjectId" column="subject_id"/>
		</collection >
	</resultMap>
	
	<sql id="commonUserColumns">id,name</sql>
	
	// resultMap
    <select id="findUserById" resultMap="userResult">
        select age,name  from t_user user  where  user.id = #{userId}
    </select>
 
    // resultType
    <select id="findUserById" resultType="User">
        select age,name  from t_user user  where  user.id = #{userId}
    </select>
   
    // foreach
	<select id="findUserByUserList" resultType="User">
        select age,name  from t_user user  where  user.id in 
 			<foreach item="user" index="index" collection="userList" open="(" separator="," close=")">
					#{user.id}
 			</foreach>
    </select>
    
    // if
    <select id="findUserByName" resultType="User">
        select age,name  from t_user user 
        <if test="null != userName and userName != ""  ">
			where user.name = #{userName}
		</if>
    </select>
  
   // include 
   <select id="findUserByName" resultType="User">
        select  <include refid="commonUserColumns" />
        from t_user user 
    </select>
   
   // 一对多 
   <select id="findUserByName" resultMap="userExt">
        select  id,name,socre,subject_id
        from t_user user left join t_score score on user.id = score.user_id 
    </select>