对于某些计算，我需要过去30天的一些表条目的总和。我的想法是做一些事情：
SELECT
a.`date`,
(SELECT COUNT(*) FROM `subtable1` AS b WHERE b.`date` = a.`date`) AS `sum1`,
(SELECT COUNT(*) FROM `subtable2` AS c WHERE c.`date` = a.`date`) AS `sum2`,
(SELECT COUNT(*) FROM `subtable3` AS d WHERE d.`date` = a.`date`) AS `sum2`
FROM
("31.05.2013", "30.05.2013", "29.05.2013") AS `date`
但是我无法弄清楚这样做的正确语法。它甚至可能吗？如果是的话，怎么样？
答案 0 :(得分：1)
试试这个：
SELECT
`date`,
SUM(IF(za_type=1,nb,0)) as sum1,
SUM(IF(za_type=2,nb,0)) as sum2,
SUM(IF(za_type=3,nb,0)) as sum3
FROM (
SELECT b.`date`,1 as za_type, COUNT(*) as nb FROM `subtable1` AS b WHERE b.`date` IN ('31-05-2013','30-05-2013','29-05.2013') UNION
SELECT c.`date`,2 as za_type, COUNT(*) as nb FROM `subtable2` AS c WHERE c.`date` IN ('31-05-2013','30-05-2013','29-05.2013') UNION
SELECT d.`date`,3 as za_type, COUNT(*) as nb FROM `subtable3` AS d WHERE d.`date` IN ('31-05-2013','30-05-2013','29-05.2013')
) as tmp
GROUP BY
`date`
更新：如果您在过去30天内需要，可以添加此条件date >= NOW() - INTERVAL 30 DAY而不是date IN (..)
UPDATE2：使用新要求（查询是过去3天）：
SELECT
za_day,
(SELECT COUNT(*) FROM subtable1 s WHERE s.date = za_day) as sum1,
(SELECT COUNT(*) FROM subtable2 s WHERE s.date = za_day) as sum2,
(SELECT COUNT(*) FROM subtable3 s WHERE s.date = za_day) as sum3
FROM (
SELECT DATE(NOW()) - INTERVAL 1 DAY as za_day UNION
SELECT DATE(NOW()) - INTERVAL 2 DAY as za_day UNION
SELECT DATE(NOW()) - INTERVAL 3 DAY as za_day
) as td
答案 1 :(得分：1)
使用来自@Vivek的UNION提示正确。解决方案是：
SELECT
`current_date`,
(SELECT COUNT(*) FROM `subtable1` AS b WHERE b.`date` = `current_date`) AS `sum1`,
(SELECT COUNT(*) FROM `subtable2` AS c WHERE c.`date` = `current_date`) AS `sum2`,
(SELECT COUNT(*) FROM `subtable3` AS d WHERE d.`date` = `current_date`) AS `sum3`
FROM
(
SELECT "31.05.2012" AS `current_date`
UNION SELECT "30.05.2012" AS `current_date`
UNION SELECT "29.05.2012" AS `current_date`
) AS `dates`
修改
因此，最终查询看起来像这样，并计算过去30天内所有广告点击次数，广告展示次数和其他一些内容（时间戳由某些php代码生成）。
SELECT
`current_timestamp`,
(
SELECT
COUNT(*)
FROM
`ad_clicks` AS a
WHERE
FLOOR(a.`timestamp` / 86400) * 86400 = `current_timestamp`
) AS `ad_click_count`,
(
SELECT
COUNT(*)
FROM
`ad_impressions` AS b
WHERE
FLOOR(b.`timestamp` / 86400) * 86400 = `current_timestamp`
) AS `ad_impression_count`,
(
SELECT
COUNT(*)
FROM
`stand_touches` AS c
WHERE
FLOOR(c.`timestamp` / 86400) * 86400 = `current_timestamp`
) AS `stand_touch_count`,
(
SELECT
COUNT(*)
FROM
`stand_url_clicks` AS d
WHERE
FLOOR(d.`timestamp` / 86400) * 86400 = `current_timestamp`
) AS `stand_url_call_count`
FROM
(
SELECT "1369958400" AS `current_timestamp` UNION
SELECT "1369872000" AS `current_timestamp` UNION
SELECT "1369785600" AS `current_timestamp` UNION
SELECT "1369699200" AS `current_timestamp` UNION
SELECT "1369612800" AS `current_timestamp` UNION
SELECT "1369526400" AS `current_timestamp` UNION
SELECT "1369440000" AS `current_timestamp` UNION
SELECT "1369353600" AS `current_timestamp` UNION
SELECT "1369267200" AS `current_timestamp` UNION
SELECT "1369180800" AS `current_timestamp` UNION
SELECT "1369094400" AS `current_timestamp` UNION
SELECT "1369008000" AS `current_timestamp` UNION
SELECT "1368921600" AS `current_timestamp` UNION
SELECT "1368835200" AS `current_timestamp` UNION
SELECT "1368748800" AS `current_timestamp` UNION
SELECT "1368662400" AS `current_timestamp` UNION
SELECT "1368576000" AS `current_timestamp` UNION
SELECT "1368489600" AS `current_timestamp` UNION
SELECT "1368403200" AS `current_timestamp` UNION
SELECT "1368316800" AS `current_timestamp` UNION
SELECT "1368230400" AS `current_timestamp` UNION
SELECT "1368144000" AS `current_timestamp` UNION
SELECT "1368057600" AS `current_timestamp` UNION
SELECT "1367971200" AS `current_timestamp` UNION
SELECT "1367884800" AS `current_timestamp` UNION
SELECT "1367798400" AS `current_timestamp` UNION
SELECT "1367712000" AS `current_timestamp` UNION
SELECT "1367625600" AS `current_timestamp` UNION
SELECT "1367539200" AS `current_timestamp` UNION
SELECT "1367452800" AS `current_timestamp`
) AS `timestamps`
答案 2 :(得分：0)
您可以设置一个临时表，并用您想要的数据填充它。
然后，您可以根据需要将现有表格加入临时表格。