mybatismapper.xml传参_动态sql

一、mapper.xml传参

　　1、根据getter和setter；

　　2、根据Map的key；

　　3、@Param("")注解；

二、动态sql

<if test="value!=null and value!=''">
    判断成功，sql语句存在；
    判断失败，sql语句不存在；
</if>

<choose>
    <when test="value!=null and value!=''">
        判断成功，执行该句
    </when>
    <otherwise>
        否则，执行该句
    </otherwise>
</choose>

<where>
    <if test="value!=null and value!=''">
        and/or要加上，开头的and/or会自动取消
    </if>
</where>

<set>
    <if test="value!=null">
        ,要加上，最后的,会自动取消
    </if>
</set>

<trim prefix="where" prefixOverrides="and | or" suffix=")" suffixOverrides=",">
    语句前加where，开头是and或or会取消，最后加)，最后是,会自动取消
</trim>

<foreach collection="list" item="item" open="(" close=")" separator=",">
    #{item},一般用于in语句或添加多行数据
</foreach>

<sql id="field">
    id,name,age
</sql>
<select id="daoMethod">
    SELECT <include refid="field"></include>
    FROM tableName
</select>

#{}和${}区别：${}是做字符串拼接，#{}是?占位，#{}比${}安全

三、级联一对多

<resultMap type="com.zhihuibao580.beans.Clargeclass" id="largeClass">
    <id column="lid" property="id"/>
    <result column="lname" property="name"></result>
    <collection property="objSubclass" ofType="com.zhihuibao580.beans.Subclass">
        <id column="sid" property="id"/>
        <result column="sname" property="name"></result>
        <result column="slargeClass" property="largeClass"></result>
        <result column="sicon" property="icon"></result>
    </collection>
</resultMap>
<select id="selectCommodityClass" resultMap="largeClass">
    select l.id lid,l.name lname,
    s.id sid,s.name sname,s.largeClass slargeClass,s.icon sicon 
    from c_largeclass l,subclass s 
    where l.id=s.largeClass
</select>

四、级联一对一

<resultMap type="com.zhihuibao580.beans.Subclass" id="mySubclass">
    <id column="sid" property="id"/>
    <result column="sname" property="name"/>
    <result column="slargeClass" property="largeClass"/>
    <result column="sicon" property="icon"/>
    <association property="clargeclass" javaType="com.zhihuibao580.beans.Clargeclass">
        <id column="lid" property="id"/>
        <result column="lname" property="name"/>
    </association>
</resultMap>
<select id="adminSelectSubclass" resultMap="mySubclass">
    select s.id sid,s.name sname,s.largeClass slargeClass,s.icon sicon,
    l.id lid,l.name lname
    from c_largeclass l,subclass s
    where s.largeClass=l.id
</select>

五、递归查询

<select id="findByArticleId" resultMap="commentResultMap">
    SELECT * FROM dcy_comment WHERE parent_id = -1
    AND article_id = #{articleId}
    ORDER BY create_date DESC
</select>
<select id="findByParentId" resultMap="commentResultMap">
    SELECT * FROM dcy_comment WHERE parent_id = #{id}
</select>
<resultMap id="commentResultMap" type="com.dingcaiyan.blog.entities.Comment">
    <id column="id" property="id"/>
    <result column="parent_id" property="parentId"/>
    <result column="user_id" property="userId"/>
    <result column="nick_name" property="nickName"/>
    <result column="user_image" property="userImage"/>
    <result column="article_id" property="articleId"/>
    <result column="content" property="content"/>
    <result column="create_date" property="createDate"/>
    <collection property="children" javaType="list" ofType="com.dingcaiyan.blog.entities.Comment" column="id"
                select="findByParentId"/>
</resultMap>