ssm/build/classes/mapper/topic.xml

<?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">
<!-- 配置关于用户评论表的 MyBatis映射文件 -->
<!-- namespace：必须与对应的接口全类名一致 id:必须与对应接口的某个对应的方法名一致 -->
<mapper namespace="com.dao.TopicDAO">
	<resultMap type="topic" id="topicMap">
		<id property="topicid" column="topicid" />
		<result property="usersid" column="usersid" />
		<result property="articleid" column="articleid" />
		<result property="contents" column="contents" />
		<result property="addtime" column="addtime" />
		<result property="username" column="username" />
		<result property="title" column="title" />
		<!-- 通过外键关联查询  返回封装Users对象 -->
		<association property="users" column="usersid" select="com.dao.UsersDAO.getUsersById" javaType="com.entity.Users" />
		<!-- 通过外键关联查询  返回封装Article对象 -->
		<association property="article" column="articleid" select="com.dao.ArticleDAO.getArticleById" javaType="com.entity.Article" />
	</resultMap>

	<!-- 用户评论表 插入SQL语句  TopicDAO通过ID(insertTopic)调用此配置 -->
	<insert id="insertTopic" parameterType="topic">  
		insert into topic(topicid  , usersid  , articleid  , contents  , addtime ) values(#{topicid}  , #{usersid}   , #{articleid}   , #{contents}   , #{addtime} )
	</insert>

	<!-- 用户评论表 更新SQL语句  TopicDAO通过ID(updateTopic)调用此配置 -->
	<update id="updateTopic" parameterType="topic">
		update topic set  usersid=#{usersid}  , articleid=#{articleid}  , contents=#{contents}  , addtime=#{addtime}  where topicid=#{topicid}
	</update>

	<!-- 用户评论表 按主键删除SQL语句  TopicDAO通过ID(deleteTopic)调用此配置 -->
	<delete id="deleteTopic" parameterType="String">
		delete from topic where topicid = #{topicid}
	</delete>

	<!-- 用户评论表 查询全部用户评论信息SQL语句  TopicDAO通过ID(getAllTopic)调用此配置  -->
	<select id="getAllTopic" resultMap="topicMap">
		select a.* , b.username , c.title  from topic a , users b , article c  where 1=1 and a.usersid = b.usersid and a.articleid = c.articleid  order by topicid desc
	</select>

	<!-- 用户评论表 按主键(topicid)查询SQL语句 TopicDAO通过ID(getTopicById)调用此配置  -->
	<select id="getTopicById" parameterType="String" resultMap="topicMap">
		select a.* , b.username , c.title  from topic a , users b , article c  where 1=1 and a.usersid = b.usersid and a.articleid = c.articleid and topicid=#{topicid} order by topicid desc
	</select>

	<!-- 用户评论表 按条件精确查询SQL语句 TopicDAO通过ID(getTopicByCond)调用此配置  -->
	<select id="getTopicByCond" parameterType="topic" resultMap="topicMap">
		select a.* , b.username , c.title  from topic a , users b , article c  where 1=1 and a.usersid = b.usersid and a.articleid = c.articleid 
		<if test="usersid != null and '' != usersid">
			and a.usersid = #{usersid}  
		</if>
		<if test="articleid != null and '' != articleid">
			and a.articleid = #{articleid}  
		</if>
		<if test="contents != null and '' != contents">
			and a.contents = #{contents}  
		</if>
		<if test="addtime != null and '' != addtime">
			and a.addtime = #{addtime}  
		</if>
	</select>

	<!-- 用户评论表 按条件模糊查询SQL语句 TopicDAO通过ID(getTopicByLike)调用此配置  -->
	<select id="getTopicByLike" parameterType="topic" resultMap="topicMap">
		select a.* , b.username , c.title  from topic a , users b , article c  where 1=1 and a.usersid = b.usersid and a.articleid = c.articleid 
		<if test="usersid != null and '' != usersid">
			and b.username like CONCAT('%', CONCAT(#{usersid}, '%'))
		</if>
		<if test="articleid != null and '' != articleid">
			and c.title like CONCAT('%', CONCAT(#{articleid}, '%'))
		</if>
		<if test="contents != null and '' != contents">
			and a.contents like CONCAT('%', CONCAT(#{contents}, '%'))
		</if>
		<if test="addtime != null and '' != addtime">
			and a.addtime like CONCAT('%', CONCAT(#{addtime}, '%'))
		</if>
	</select>
</mapper>