目录

1. Model : XxxMapper.xml

1. IotTypeMapper.xml 基础 × 3 tips

2. Model : XxxMapper.java

1. IotTypeMapper.java 基础 × 3 tips

3. Others info

1. 模糊查询

2. 模糊查询 'name' 导致的异常 --> `name

3. 连接查询 Where 限制主表 , 谨慎 : 使用副表限制 - ★

4. 数据去重 : group by | distinct ( 视情况选择 )

5. 以 map 为查询条件的 API

6. 标签判断处理 : String / 集合 / 基本数据类型参数为 0

7. 将 null 值更新到数据库

---

1. Model : XxxMapper.xml

---

1. IotTypeMapper.xml 基础 × 3 tips

    <!-- IotTypeVO查询映射结果 -->
    <resultMap id="IotTypeVOResultMap" type="com.hzcloud.iot.resource.vo.IotTypeVO">
        <result column="id" property="id" />
        <result column="name" property="name" />
        <result column="type" property="type" />
        <result column="attribute" property="attribute" />
        <result column="status" property="status" />
        <result column="create_time" property="createTime" />
        <result column="update_time" property="updateTime" />
        <result column="del_flag" property="delFlag" />
    </resultMap>

    <!-- 通用查询结果列 -->
    <sql id="Base_Column_List">
        id ,  name ,  type ,  attribute ,  status ,  create_time ,  update_time ,  del_flag
    </sql>

    <!-- 无参查询房源类型List -->
    <select id="queryIotTypeList"  resultMap="BaseResultMap">
        SELECT
        <include refid="Base_Column_List" />
        FROM iot_type
        WHERE del_flag = 0 AND status = 0
        ORDER BY create_time DESC
    </select>

    <!-- 条件查询类型字段List -->
    <select id="queryByConditions"  resultMap="BaseResultMap">
        SELECT
        <include refid="Base_Column_List" />
        FROM iot_type
        <where>
            del_flag = 0
            <if test="iotTypeDTO.type != null and iotTypeDTO.type != '' ">
                AND type = #{iotTypeDTO.type}
            </if>
            <if test="iotTypeDTO.status == null or iotTypeDTO.status == '' ">
                AND status in (0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9)
            </if>
            <if test="iotTypeDTO.status != null and iotTypeDTO.status != '' ">
                AND status = #{iotTypeDTO.status}
            </if>
        </where>
        ORDER BY create_time DESC
    </select>

优化纪录

1、查存时增加状态 status 条件 , 启动 status 禁用全局隐藏机制 - 20.10.24

---

2. Model : XxxMapper.java

---

1. IotTypeMapper.java 基础 × 3 tips

    /**
     * 无参查询资源类型List
     * @return 资源类型展示对象集合IotTypeVOList
     */
    List<IotTypeVO> queryIotTypeList();

    /**
     * 条件查询资源类型List
     * @param iotTypeDTO 资源类型接收入参DTO
     * @return 资源类型展示对象集合IotTypeVOList
     */
    List<IotTypeVO> queryByConditions(@Param("iotTypeDTO") IotTypeDTO iotTypeDTO);

    /**
     * 条件查询资源类型Page
     * @param page 分页参数
     * @param iotTypeDTO 资源类型接收入参DTO
     * @return 资源类型展示对象集合IotTypeVOList
     */
    IPage<IotTypeVO> queryByConditions(@Param("page")Page page ,  @Param("iotTypeDTO") IotTypeDTO iotTypeDTO);

---

3. Others info

---

1. 模糊查询

    <if test="userDTO.name != null and userDTO.name != ''">
        and u.name like CONCAT('%' , #{userDTO.name} , '%')
    </if>

%通配符使用

-- 匹配以"yves"开头的记录:(包括记录"yves")
SELECT * FROM products WHERE products.prod_name like 'yves%';

-- 匹配包含"yves"的记录(包括记录"yves")
SELECT * FROM products WHERE products.prod_name like '%yves%';

-- 匹配以"yves"结尾的记录(包括记录"yves" , 不包括记录"yves " , 也就是yves后面有空格的记录 , 这里需要注意)
SELECT * FROM products WHERE products.prod_name like '%yves';

_ 通配符使用

--匹配结果为: 像"yyves"这样记录.
SELECT * FROM products WHERE products.prod_name like '_yves';

--匹配结果为: 像"yvesHe"这样的记录.(一个下划线只能匹配一个字符 , 不能多也不能少)
SELECT * FROM products WHERE products.prod_name like 'yves__';

---

2. 模糊查询 'name' 导致的异常 --> `name

         <if test="iotTypeDTO.name != null and iotTypeDTO.name != '' ">
                AND 'name' like CONCAT('%' , #{iotTypeDTO.name} , '%')
            </if>

 导致模糊查询 name 参数失效

API 调用返回结果集 : {}

修改

            <if test="iotTypeDTO.name != null and iotTypeDTO.name != '' ">
                AND name like CONCAT('%' , #{iotTypeDTO.name} , '%')
            </if>

---

3. 连接查询 Where 限制主表 , 谨慎 : 使用副表限制 - ★

SELECT
img.id ,  img.name ,  img.cause ,  img.tenant_id ,  img.room_id ,  img.compere_id ,  img.preparer_id ,  img.type ,  img.level ,  img.start_time ,  img.end_time , 
img.introduction ,  img.status ,  img.create_time ,  img.update_time ,  img.del_flag ,  irm.structure_id  , irm.name AS roomName
FROM iot_meeting img
LEFT JOIN iot_room irm ON img.room_id = irm.id
WHERE
img.del_flag = 0 AND irm.del_flag = 0
AND to_days(img.start_time) = to_days("2021-04-015 12:00:00")

SELECT
img.id ,  img.name ,  img.cause ,  img.tenant_id ,  img.room_id ,  img.compere_id ,  img.preparer_id ,  img.type ,  img.level ,  img.start_time ,  img.end_time , 
img.introduction ,  img.status ,  img.create_time ,  img.update_time ,  img.del_flag ,  irm.structure_id  , irm.name AS roomName
FROM iot_meeting img
LEFT JOIN iot_room irm ON img.room_id = irm.id
WHERE
img.del_flag = 0 AND irm.del_flag = 0
AND to_days(img.start_time) = to_days("2021-04-015 12:00:00")

---

4. 数据去重 : group by | distinct ( 视情况选择 )

---

5. 以 map 为查询条件的 API

---

6. <if> 标签判断处理 : String / 集合 / 基本数据类型参数为 0

---

7. 将 null 值更新到数据库