今天完成的事情：今天顺利完成第一次小课堂，有些小紧张，中间代码运行出错，还好自己稳住解决了，然后就是做小课堂的后续工作，因为第一次做，还不知道完整步骤。
明天计划的事情：看看能不能把任务四给了结了。
遇到的问题：暂无
收获：今天收获就是更加熟悉动态SQL,对Mybatis加深了记忆，讲出来的东西是不一样，虽然讲的很菜，但是自己收获最大。

<!--动态update-set-->
    <update id="updateOne" parameterType="Item">
        update item 
        <set>
            <if test="name != null">name=#{name}</if>
            <if test="state != null">state=#{state}</if>
        </set>
        where id=#{id}
    </update>
    <!--sql重用-->
    <sql id="forItem">id,name,intro,catalog_id,shop_id,price,state,create_at,update_at</sql>
    <!--if标签，根据状态（上架/下架）和商品的分类和店铺名查找所有符合条件的商品-->
    <select id="selectMore" resultType="Item" >
        select <include refid="forItem"></include> from item
        where state = #{state}
        <if test="name!=null">
            and name=#{name}
        </if>
        <if test="catalogId != 0">
            and catalog_id=#{catalogId}
        </if>
        <if test="shopId != 0">
            and shop_id=#{shopId}
        </if>
        <if test="craeateAt !=0 ">
            and create_at=#{craeateAt}
        </if>
    </select>
    <!--where标签-->
    <select id="selectMore" resultType="Item" >
        select <include refid="forItem"></include> from item
        <where>
            <if test="state !=0 ">
                and state = #{state}
            </if>
            <if test="name!=null and name!=''">
            and name=#{name}
            </if>
            <if test="catalogId != 0">
                and catalog_id=#{catalogId}
            </if>
            <if test="shopId != 0">
                and shop_id=#{shopId}
            </if>
        </where>
    </select>
<!--    动态choose-when-otherwise-->
    <select id="selectMore" resultType="Item">
        select <include refid="forItem"></include> from item
        <where>
            <choose>
                <when test="state != 0">
                    state = #{state}
                </when>
                <otherwise>
                    state = #{state}
                </otherwise>
            </choose>
        </where>
    </select>
<!--trim标签使用-->
        <update id="updateOne" parameterType="Item">
            update item
            <trim prefix="set" suffixOverrides=",">
                <if test="name != null">name=#{name},</if>
                <if test="state != null">state=#{state},</if>
            </trim>
            where id=#{id}
        </update>
    <!-- 上面的可用trim替换 -->
    <select id="selectMore" resultType="Item" >
        select <include refid="forItem"></include> from item
        <trim prefix="where" prefixOverrides="and">
            <if test="state !=0 ">
                and state = #{state}
            </if>
            <if test="name!=null and name!=''">
                and name=#{name}
            </if>
            <if test="catalogId != 0">
                and catalog_id=#{catalogId}
            </if>
            <if test="shopId != 0">
                and shop_id=#{shopId}
            </if>
        </trim>
    </select>
    <!--foreach标签，批量插入-->
    <sql id="insertItem">name,intro,catalog_id,shop_id,price,state,create_at,update_at</sql>
    <insert id="insertMore" parameterType="List" useGeneratedKeys="true" keyProperty="id">
        insert into item (<include refid="insertItem"></include>)
        values
        <foreach collection="list" item="item" separator=",">
            (#{item.name},#{item.intro},#{item.catalogId},#{item.shopId},#{item.price},#{item.state},#{item.createAt},#{item.updateAt})
        </foreach>
    </insert>
    <!--foreach标签,批量删除-->
    <delete id="deleteMore" >
        delete from item where id in
        <foreach collection="array" item="item" open="(" separator="," close=")">
            #{item}
        </foreach>
    </delete>