mybatis中使用in查询时的注意事项

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一、当查询的参数只有一个时
findByIds(List ids)
a. 如果参数的类型是List, 则在使用时，collection属性要必须指定为 list

 <select id="getPostOrderListByParam"        resultType="com.qlyd.common.po.post.PostInfo"        parameterType="com.qlyd.common.inparam.manage.postmanage.PostManageQueryParam">                select inner_id,circle_id, user_id, user_type,                 word_content, img_content, status, publish_time, comment_sum,                 view_sum, order_num, perfect_num from circle_posts_info                 WHERE                <if test="circle_id !=null">                circle_id=#{circle_id} and order_num !=1000                     <if test="postids !=null">                    or inner_id in                        <foreach item="item" index="index" collection="postids"                          open="(" separator="," close=")">                            #{item}                        </foreach>                    </if>                     order by order_num,publish_time DESC                </if>                <if test="circle_id ==null">                perfect_num !=1000                     <if test="postids !=null">                    or inner_id in                    <foreach item="item" index="index" collection="postids"                          open="(" separator="," close=")">                            #{item}                        </foreach>                    </if>                    order by perfect_num,publish_time DESC                 </if>    </select>

findByIds(Long[] ids)
b. 如果参数的类型是Array,则在使用时，collection属性要必须指定为 array

 <select id="findByIdsMap" resultMap="BaseResultMap">                 select                 <include refid="Base_Column_List" />          from jria where ID in                  <foreach item="item" index="index" collection="array"                          open="(" separator="," close=")">                        #{item}                </foreach>  </select>

二、当查询的参数有多个时,例如 findByIds(String name, Long[] ids)
这种情况需要特别注意，在传参数时，一定要改用Map方式, 这样在collection属性可以指定名称
下面是一个示例

         Map<String, Object> params = new HashMap<String, Object>(2);        params.put("name", name);         params.put("ids", ids);        mapper.findByIdsMap(params); <select id="findByIdsMap" resultMap="BaseResultMap">                 select                 <include refid="Base_Column_List" />          from jria where ID in                  <foreach item="item" index="index" collection="ids"                          open="(" separator="," close=")">                        #{item}                </foreach>   </select>

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