Question

我有桌子：

-Parts-
ID
name

-ReportA-
ID
PART_ID
LOCATION_ID
GPS_ID
USER_ID
VALVE_ID
DATE

-ReportB-
ID
PART_ID
LOCATION_ID
TYPE_ID
NOTES
GPS_ID
DATE

（1）我想抓住所有有报告A或B的部分：

SELECT
    *
FROM
    parts
WHERE
    id IN (SELECT id FROM reports_a UNION SELECT id FROM reports_b

完美（1）但是现在我需要从最近的报告（A或B）中获取LOCATION_ID和GPS_ID。

示例：

-Parts-
1
Valve

-ReportA-
1
1
4
9
2
12
2013-02-01

-ReportB-
1
1
113
3
"Changed part"
90
2013-03-27

所以我需要一个可以获取所有部分及其最新位置和gps id的SQL脚本，上面的结果会产生：

PART_ID = 1
LOCATION_ID = 113
GPS_ID = 90

所以我将我的SQL脚本从之前改为：

SELECT
    id AS PART_ID
    (
        (
           SELECT location_id FROM reports_a ORDER BY date DESC
           UNION
           SELECT location_id FROM reports_b ORDER BY date DESC
        )
        ORDER BY
           date DESC
        LIMIT 1  
    ) AS LOCATION_ID
FROM
    parts
WHERE
    id IN (SELECT id FROM reports_a UNION SELECT id FROM reports_b

但是，我不能按日期DESC订购，因为它不是UNION返回的字段？

任何想法??

Answer 1

更新：我似乎误读了之前的问题，以下查询获取了特定product_id的最新数据

SELECT 
    id,
    name,
    (
      SELECT 
        CONCAT( 'Location_id: ',location_id, ' gps_id: ', gps_id, ' date: ', `date` )
      FROM 
        ( SELECT `date`,part_id, location_id, gps_id FROM reportA
        UNION 
        SELECT `date`,part_id, location_id, gps_id FROM reportB
        ) t
      WHERE part_id = p.id  
      ORDER BY `date` desc 
      LIMIT 1) 
    as details
FROM 
    parts p

<强> SQLFiddle

您使用的结构不正确，理想情况下，您应该将所有report_data放在一个表格中report_type可能是A或B

的列表中

学习SQL，抓住最新的配置

1 个答案: