Mybatis传多个参数的五个方法

一、实体类+@Param注解传参（难点，重点，基本会这个就行了）

在我们拥有多个参数的时候，怎么让传入xml文件的参数，选中我们需要的实体类部分，就需要加入@Param注解，在xml中使用注解里面的值，如下面代码，我在@Param中加入了competitionVo就需要在xml中，点出来，如competitionVo.singerName和#{competitionVo.singerName}

Mapper

Page<Competition> competitionInfoPart(Page page,@Param("competitionVo") CompetitionVo competitionVo);

Mapper.xml（不需要看我的SQL，主要理解@Param注解+实体类的使用）

<select id="competitionInfoPart" resultMap="info" parameterType="com.zhao.pojo.CompetitionVo">
        select c.*,
               s1.singer_name singer1Name,s2.singer_name singer2Name
        FROM competition c
            INNER JOIN singer s1 on c.singer1_id=s1.singer_id
            INNER JOIN singer s2 on c.singer2_id=s2.singer_id
        where c.deleted = 0
        <if test="competitionVo.singerName!=null">
            and (s1.singer_name like CONCAT(%,#{competitionVo.singerName},%) or s2.singer_name like CONCAT(%,#{competitionVo.singerName},%))
        </if>
        <if test="competitionVo.song!=null">
            and (c.singer2_song like CONCAT(%,#{competitionVo.song},%) or c.singer1_song like CONCAT(%,#{competitionVo.song},%) )
        </if>
        <if test="competitionVo.status!=null">
            and (c.competition_state = #{competitionVo.status} or c.competition_state = #{competitionVo.status})
        </if>
        order by c.competition_id desc
    </select>

二、实体类传参（重点，经常使用）

Mapper

User selectUser(User user);

Mapper.xml

<select id="selectUser" parameterType="com.zhao.User" resultType="com.zhao.User">
    select * from user
    where user_name = #{userName} and id = #{id}
</select>

三、@Param传参（重点）

基本类型（int、String…）这样的不需要写 parameterType 写也可以

Mapper

User selectUser(@Param("userName") String name, @Param("id") int id);

Mapper.xml

<select id="selectUser"  resultType="com.zhao.User">
    select * from user
    where user_name = #{userName} and id = #{id}
</select>

四、顺序传参（不建议）

Mapper

User selectUser(String name, int id);

Mapper.xml

<select id="selectUser"  resultType="com.zhao.User">
    select * from user
    where user_name = #{name} and id = #{id}
</select>

五、Map传参（不常用）

Mapper

User selectUser(Map<String, Object> user);

Mapper.xml

<select id="selectUser" parameterType="Map" resultType="com.zhao.User">
    select * from user
    where user_name = #{name} and id = #{id}
</select>

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