mybatis常用写法

xml中使用常量

yml文件中
imgLoc=http://127.0.0.1:8080/app/public/img/icon.png

常量类中
@Component
public class Constant {
    @Value("${imgLoc}")
    String imgLoc;
}

xml语法中
<sql id="baseConsts">
        <bind name="DEFAULT_PIC" value="@com.zmd.sys.constants.Constant@imgLoc"/>
</sql>

<!-- 通用查询结果列 -->
<sql id="Base_Column_List">
       a.order_discuss_id AS "orderDiscussId",
       a.order_id AS "orderId"
</sql>


<select id="orders">
        <include refid="baseConsts" />
        select #{imgLoc} imgLoc, <include refid="Base_Column_List" /> from orders
</select>

一对多写法1

@Select("select img from jc_img where is_del = 0 and content_id = #{contentId}")
List<Integer> img(@Param("contentId")Integer contentId);

@Select("select channel_id from jc_channel where is_del = 0 and content_id = #{contentId}")
List<Integer> channel(@Param("contentId")Integer contentId);

<resultMap id="ResultMap" type="com.zmd.sys.vo.content.response.ContentListResponse">
    <association property="imgPaths" column="content_id" select="com.zmd.sys.mapper.content.ContentPictureMapper.img"/>
    <association property="channels" column="content_id" select="com.zmd.sys.mapper.channel.ChannelMapper.channel"/>
</resultMap>

<select id="contentList" resultMap="ResultMap">
    select a.content_id contentId,a.content_id from jc_content 
</select>

一对多写法2

//查询 文章详情
@Results({
        @Result(property = "imgPaths",column = "content_id",many = @Many(select = "com.zmd.sys.mapper.content.ContentPictureMapper.selectImgPathByContentId")),
        @Result(property = "channel",column = "content_id",many = @Many(select = "com.zmd.sys.mapper.content.ContentChannelMapper.selectChannelIdsByContentId")),
        @Result(property = "area",column = "content_id",many = @Many(select = "com.zmd.sys.mapper.content.ContentAreaMapper.selectAreaIdsByContentId"))
})
@Select("select a.content_id contentId,a.content_id,a.status,b.author_name,b.origin,b.title,b.short_title,b.title_img," +
        "b.media_times,b.media_path,b.characters,b.release_date,c.txt text " +
        "from jc_content a " +
        "left join jc_content_ext b on a.content_id=b.content_id " +
        "left join jc_content_txt c on a.content_id=c.content_id " +
        "where a.content_id=#{contentId}")
SysContentDetailResponse detailContentById(@Param("contentId") Integer contentId);

if 语法  choose when otherwise(=else if)语法  foreach语法

<if test="param.channelId != null and param.channelId !='' ">
    <choose>
        <when test="param.isSubChannel == 1">
            and d.channel_id in
            <foreach collection="channels" item="channelId" index="index" open="(" close=")" separator=",">
                 #{channelId}
            </foreach>
        </when>
        <otherwise>
            and d.channel_id=#{param.channelId}
        </otherwise>
    </choose>
</if>

 

来源：oschina

链接：https://my.oschina.net/xhbl/blog/4381715