Question

我有一个数据库，其中包含两个时区内多个站点的事件，并且都报告了当地时间。我需要获取最近12小时的数据并将其放入CSV格式。我输入了一个联合，当它输出没有ORDER BY的数据时，我在使用INTO OUTFILE部分运行它时会出现别名错误。我错过了什么？

(SELECT
    comp.locationid,
    comp.name,
    event.status,
    event.starttime,
    event.endtime
FROM
    comp,event
WHERE
    event.endtime >= DATE_SUB(NOW(), INTERVAL 12 HOUR)
    AND event.endtime < NOW()
    AND event.compid = comp.id
    AND comp.timezone = "EST")


UNION


(SELECT
    comp.locationid,
    comp.name,
    event.status,
    event.starttime,
    event.endtime
FROM
    comp,event
WHERE
    event.endtime >= DATE_SUB(NOW(), INTERVAL 15 HOUR)
    AND event.endtime < DATE_SUB(NOW(), INTERVAL 3 HOUR)
    AND event.compid = comp.id
    AND comp.timezone = "PST")


ORDER BY comp.locationid
INTO OUTFILE
    "report.csv"
FIELDS TERMINATED BY ','
LINES TERMINATED BY '\r\n'
;

Answer 1

为表格提供别名会有所帮助

(SELECT
    comp.locationid,
    comp.name,
    event.status,
    event.starttime,
    event.endtime
FROM
    comp,event
WHERE
    event.endtime >= DATE_SUB(NOW(), INTERVAL 12 HOUR)
    AND event.endtime < NOW()
    AND event.compid = comp.id
    AND comp.timezone = "EST") AS T


UNION ALL


(SELECT
    comp.locationid,
    comp.name,
    event.status,
    event.starttime,
    event.endtime
FROM
    comp,event
WHERE
    event.endtime >= DATE_SUB(NOW(), INTERVAL 15 HOUR)
    AND event.endtime < DATE_SUB(NOW(), INTERVAL 3 HOUR)
    AND event.compid = comp.id
    AND comp.timezone = "PST") AS T2
ORDER BY comp.locationid
INTO OUTFILE
    "report.csv"
FIELDS TERMINATED BY ','
LINES TERMINATED BY '\r\n'
;

Answer 2

<强>更新：

您无法在ORDER BY的{{1}}子句中引用特定的表名。据说只是改变
```
UNION
```
简单地
```
ORDER BY comp.locationid
         ^^^^^
```
此外，您似乎最有可能使用ORDER BY locationid代替UNION ALL。所以也要改变它，因为UNION需要额外的处理步骤来消除重复。
删除UNION

SELECT

将所有双引号更改为单引号

组合来自同一组数据的两个基于时间的查询

2 个答案: