Question

我有一个MySQL查询，利用COALESCE来回溯NULL值，并为这些NULL值分配它找到的第一个NON-NULL值。

通过使用不推荐使用的函数mysql_query以及使用mysqli并调用存储过程本身从PHP脚本中解决此查询，不会影响任何行;但是，如果我手动运行查询，或者手动调用存储过程，则会正确更新行，从而生成所需的结果集。

DDL：

CREATE TABLE IF NOT EXISTS `file_index` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `file_id` int(10) unsigned NOT NULL,
  `page` int(10) unsigned NOT NULL,
  `user_id` int(10) unsigned NOT NULL,
  `made` datetime DEFAULT NULL,
  `current` tinyint(3) unsigned DEFAULT '1',
  `code` char(5) NOT NULL,
  `idnumber` int(10) unsigned DEFAULT NULL,
  `deconstructed` int(1) NOT NULL DEFAULT '0',
  PRIMARY KEY (`id`),
  KEY `file_id` (`file_id`,`page`),
  KEY `user_id` (`user_id`),
  KEY `idnumber` (`idnumber`)
) ENGINE=MyISAM AUTO_INCREMENT=25 DEFAULT CHARSET=latin1 ROW_FORMAT=FIXED;
INSERT INTO `file_index` (`id`, `file_id`, `page`, `user_id`, `made`, `current`, `code`, `idnumber`, `deconstructed`) VALUES
    (2, 637847, 2, 473, '2014-06-23 00:00:00', 1, 'INIT', 1737929, 0),
    (3, 637847, 3, 473, '2014-06-23 00:00:00', 1, 'CONT', NULL, 0),
    (4, 637847, 4, 473, '2014-06-23 00:00:00', 1, 'INIT', 85956, 0),
    (5, 637847, 5, 473, '2014-06-23 00:00:00', 1, 'INIT', 163262, 0),
    (6, 637847, 6, 473, '2014-06-23 00:00:00', 1, 'INIT', 1171457, 0),
    (7, 637847, 7, 473, '2014-06-23 00:00:00', 1, 'INIT', 1173838, 0),
    (8, 637847, 8, 473, '2014-06-23 00:00:00', 1, 'INIT', 2264105, 0),
    (9, 637847, 9, 473, '2014-06-23 00:00:00', 1, 'INIT', 2084006, 0),
    (10, 637847, 10, 473, '2014-06-23 00:00:00', 1, 'INIT', 1298597, 0),
    (11, 637847, 11, 473, '2014-06-23 00:00:00', 1, 'INIT', 2263042, 0),
    (12, 637847, 12, 473, '2014-06-23 00:00:00', 1, 'INIT', 1288872, 0),
    (13, 637847, 13, 473, '2014-06-23 00:00:00', 1, 'CONT', NULL, 0),
    (15, 637845, 2, 79, '2014-06-23 00:00:00', 1, 'INIT', 2264143, 0),
    (16, 637845, 3, 79, '2014-06-23 00:00:00', 1, 'CONT', NULL, 0),
    (17, 637845, 4, 79, '2014-06-23 00:00:00', 1, 'INIT', 2019138, 0),
    (18, 637845, 5, 79, '2014-06-23 00:00:00', 1, 'INIT', 157726, 0),
    (19, 637845, 6, 79, '2014-06-23 00:00:00', 1, 'INIT', 2087837, 0),
    (22, 637845, 9, 79, '2014-06-23 00:00:00', 1, 'INIT', 2264118, 0),
    (23, 637845, 10, 79, '2014-06-23 00:00:00', 1, 'INIT', 2264124, 0),
    (24, 637845, 11, 79, '2014-06-23 00:00:00', 1, 'CONT', NULL, 0);

链接到SqlFiddle：http://sqlfiddle.com/#!2/6e79d

查询：

UPDATE file_index
SET idnumber = (@n := COALESCE(idnumber, @n))
ORDER BY file_id, page ASC

当前结果集：

+----------+------+----------+
| file_id  | page | idnumber |
+----------+------+----------+
|   637847 |    2 |  1737929 |
|   637847 |    3 |     NULL |
|   637847 |    4 |    85956 |
|   637847 |    5 |   163262 |
|   637847 |    6 |  1171457 |
|   637847 |    7 |  1173838 |
|   637847 |    8 |  2264105 |
|   637847 |    9 |  2084006 |
|   637847 |   10 |  1298597 |
|   637847 |   11 |  2263042 |
|   637847 |   12 |  1288872 |
|   637847 |   13 |     NULL |
|   637845 |    2 |  2264143 |
|   637845 |    3 |     NULL |
|   637845 |    4 |  2019138 |
|   637845 |    5 |   157726 |
|   637845 |    6 |  2087837 |
|   637845 |    9 |  2264118 |
|   637845 |   10 |  2264124 |
|   637845 |   11 |     NULL |
+----------+------+----------+

所需的结果集：

+----------+------+----------+
| file_id  | page | idnumber |
+----------+------+----------+
|   637847 |    2 |  1737929 |
|   637847 |    3 |  1737929 |
|   637847 |    4 |    85956 |
|   637847 |    5 |   163262 |
|   637847 |    6 |  1171457 |
|   637847 |    7 |  1173838 |
|   637847 |    8 |  2264105 |
|   637847 |    9 |  2084006 |
|   637847 |   10 |  1298597 |
|   637847 |   11 |  2263042 |
|   637847 |   12 |  1288872 |
|   637847 |   13 |  1288872 |
|   637845 |    2 |  2264143 |
|   637845 |    3 |  2264143 |
|   637845 |    4 |  2019138 |
|   637845 |    5 |   157726 |
|   637845 |    6 |  2087837 |
|   637845 |    9 |  2264118 |
|   637845 |   10 |  2264124 |
|   637845 |   11 |  2264124 |
+----------+------+----------+

Answer 1

无论出于何种原因，我必须运行两次查询才能生效并更新行。奇怪的是，但是如果我开火两次它就会起作用。

使用Coalesce的Mysql查询不会更新行

1 个答案: