架构：
-- phpMyAdmin SQL Dump
-- version 3.4.5
-- http://www.phpmyadmin.net
SET SQL_MODE="NO_AUTO_VALUE_ON_ZERO";
SET time_zone = "+00:00";
CREATE TABLE IF NOT EXISTS `links` (
`pageId` int(10) unsigned NOT NULL,
`linkId` int(10) unsigned NOT NULL,
`whenUsed` datetime NOT NULL,
`whenRendered` datetime NOT NULL,
KEY `pageId` (`pageId`),
KEY `linkId` (`linkId`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
INSERT INTO `links` (`pageId`, `linkId`, `whenUsed`, `whenRendered`) VALUES
(1, 9, '2013-02-14 00:44:20', '2013-02-14 00:42:39'),
(1, 9, '2013-02-14 00:44:21', '2013-02-14 00:42:39'),
(1, 9, '2013-02-14 00:44:23', '2013-02-14 00:44:21'),
(1, 8, '2013-02-14 00:44:25', '2013-02-14 00:44:23'),
(1, 7, '2013-02-14 00:44:26', '2013-02-14 00:44:25'),
(1, 6, '2013-02-14 00:44:28', '2013-02-14 00:44:26'),
(1, 3, '2013-02-14 00:44:29', '2013-02-14 00:44:26'),
(1, 7, '2013-02-14 00:44:31', '2013-02-14 00:44:29'),
(1, 8, '2013-02-14 00:44:32', '2013-02-14 00:44:31'),
(1, 11, '2013-02-14 00:44:34', '2013-02-14 00:44:32');
内部查询：
SELECT `linkId`,
TIMEDIFF(`whenUsed`, `whenRendered`) AS 'URDiff',
CONVERT(DATEDIFF(`whenUsed`, UTC_TIMESTAMP()), SIGNED) AS 'dateDiff',
CONVERT('dateDiff' = 0, UNSIGNED) AS 'usedToday',
CONVERT('dateDiff' < 8 AND 'dateDiff' > 0, UNSIGNED) AS 'usedThisWeek',
CONVERT('dateDiff' < 31 AND 'dateDiff' > 7, UNSIGNED) AS 'usedThisMonth',
CONVERT('dateDiff' < 365 AND 'dateDiff' > 30, UNSIGNED) AS 'usedThisYear'
FROM `links`
WHERE MINUTE('URDiff') < 15 AND HOUR('URDiff') = 0
AND `pageId` = '1'
) AS T
内部查询的结果：
+--------+----------+----------+-----------+--------------+---------------+--------------+
| linkId | URDiff | dateDiff | usedToday | usedThisWeek | usedThisMonth | usedThisYear |
+--------+----------+----------+-----------+--------------+---------------+--------------+
| 9 | 00:01:41 | 0 | 1 | 0 | 0 | 0 |
| 9 | 00:01:42 | 0 | 1 | 0 | 0 | 0 |
| 9 | 00:00:02 | 0 | 1 | 0 | 0 | 0 |
| 8 | 00:00:02 | 0 | 1 | 0 | 0 | 0 |
| 7 | 00:00:01 | 0 | 1 | 0 | 0 | 0 |
| 6 | 00:00:02 | 0 | 1 | 0 | 0 | 0 |
| 3 | 00:00:03 | 0 | 1 | 0 | 0 | 0 |
| 7 | 00:00:02 | 0 | 1 | 0 | 0 | 0 |
| 8 | 00:00:01 | 0 | 1 | 0 | 0 | 0 |
| 11 | 00:00:02 | 0 | 1 | 0 | 0 | 0 |
+--------+----------+----------+-----------+--------------+---------------+--------------+
外部查询：
SELECT
`linkId`,
SUM('T.usedToday') AS 'countToday',
SUM('T.usedThisWeek') AS 'countThisWeek',
SUM('T.usedThisMonth') AS 'countThisMonth',
SUM('T.usedThisYear') AS 'countThisYear'
FROM
(
SELECT `linkId`,
TIMEDIFF(`whenUsed`, `whenRendered`) AS 'URDiff',
CONVERT(DATEDIFF(`whenUsed`, UTC_TIMESTAMP()), SIGNED) AS 'dateDiff',
CONVERT('dateDiff' = 0, UNSIGNED) AS 'usedToday',
CONVERT('dateDiff' < 8 AND 'dateDiff' > 0, UNSIGNED) AS 'usedThisWeek',
CONVERT('dateDiff' < 31 AND 'dateDiff' > 7, UNSIGNED) AS 'usedThisMonth',
CONVERT('dateDiff' < 365 AND 'dateDiff' > 30, UNSIGNED) AS 'usedThisYear'
FROM `links`
WHERE MINUTE('URDiff') < 15 AND HOUR('URDiff') = 0
AND `pageId` = '1'
) AS T
GROUP BY `linkId`
外部查询结果：
+--------+------------+---------------+----------------+---------------+
| linkId | countToday | countThisWeek | countThisMonth | countThisYear |
+--------+------------+---------------+----------------+---------------+
| 3 | 0 | 0 | 0 | 0 |
| 6 | 0 | 0 | 0 | 0 |
| 7 | 0 | 0 | 0 | 0 |
| 8 | 0 | 0 | 0 | 0 |
| 9 | 0 | 0 | 0 | 0 |
| 11 | 0 | 0 | 0 | 0 |
+--------+------------+---------------+----------------+---------------+
去图？我可以从内部结果中清楚地看到usedToday列中有3行是1（并且我已经将它们转换为unsigned，因此它们应该为SUM确定）对于linkId 9.然而，linkId 9的countToday是0而不是3。为什么呢？
MySQL给了我一些有趣的警告：Warning (Code 1292): Truncated incorrect time value: 'URDiff'
Warning (Code 1292): Truncated incorrect time value: 'URDiff'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'dateDiff'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'dateDiff'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'dateDiff'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'dateDiff'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'dateDiff'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'dateDiff'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'dateDiff'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedToday'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisWeek'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisMonth'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisYear'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedToday'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisWeek'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisMonth'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisYear'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedToday'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisWeek'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisMonth'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisYear'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedToday'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisWeek'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisMonth'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisYear'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedToday'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisWeek'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisMonth'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisYear'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedToday'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisWeek'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisMonth'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisYear'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedToday'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisWeek'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisMonth'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisYear'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedToday'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisWeek'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisMonth'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisYear'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedToday'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisWeek'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisMonth'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisYear'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedToday'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisWeek'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisMonth'
Warning (Code 1292): Truncated incorrect DOUBLE value: 'T.usedThisYear'
从我在网上找到的关于这个警告的内容来看，似乎有些人没有在他们的名字上使用引号（我到处都使用）。现在为什么解析器会为报价使用提供这样的警告？
答案 0 :(得分：2)
爸爸！这是有效的查询：
SELECT
`linkId`,
SUM(T.usedToday)ascountToday,
SUM(T.usedThisWeek)as countThisWeek,
SUM(T.usedThisMonth)as countThisMonth,
SUM(T.usedThisYear)as countThisYear
FROM
(
SELECT `linkId`,
TIMEDIFF(`whenUsed`, `whenRendered`) as URDiff,
DATEDIFF(`whenUsed`, UTC_TIMESTAMP()) as `dateDiff`,
if(DATEDIFF(`whenUsed`, UTC_TIMESTAMP()) = 0, 1, 0)as usedToday,
if(DATEDIFF(`whenUsed`, UTC_TIMESTAMP()) < 8 AND DATEDIFF(`whenUsed`, UTC_TIMESTAMP()) > 0, 1, 0)as usedThisWeek,
if(DATEDIFF(`whenUsed`, UTC_TIMESTAMP()) < 31 AND DATEDIFF(`whenUsed`, UTC_TIMESTAMP()) > 7, 1, 0) as usedThisMonth,
if(DATEDIFF(`whenUsed`, UTC_TIMESTAMP()) < 365 AND DATEDIFF(`whenUsed`, UTC_TIMESTAMP()) > 30, 1, 0) as usedThisYear
FROM `links`
WHERE MINUTE(TIMEDIFF(`whenUsed`, `whenRendered`)) < 15 AND HOUR(TIMEDIFF(`whenUsed`, `whenRendered`)) = 0
AND `pageId` = 1
) as T
GROUP BY `linkId`