解決mysql 修改表記錄 1093錯誤

1.需求 ：

已知表信息如下 ：

表名 ：frjg

表結構：

DROP TABLE IF EXISTS `frjg`;
CREATE TABLE IF NOT EXISTS `frjg` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `jgbh` varchar(3) CHARACTER SET utf8 NOT NULL COMMENT '法人機構編號',
  `jgmc` varchar(50) CHARACTER SET utf8 NOT NULL COMMENT '機構名稱',
  `jgm` varchar(8) CHARACTER SET utf8 NOT NULL COMMENT '機構碼',
  `htqssj` date NOT NULL COMMENT '合同起始時間',
  `htyxsj` date NOT NULL COMMENT '合同有效時間',
  `dxfsl` int(11) NOT NULL COMMENT '短信發送總量',
  `dxsyl` int(11) NOT NULL COMMENT '短信剩餘量',
  `mbkhl` int(11) NOT NULL COMMENT '目標客戶量',
  `cjsj` datetime NOT NULL COMMENT '創建時間',
  `lastactive` datetime NOT NULL COMMENT '最後一次操作時間',
  `xmmc` varchar(50) CHARACTER SET utf8 NOT NULL COMMENT '項目名稱',
  `cjr` varchar(50) CHARACTER SET utf8 DEFAULT NULL COMMENT '創建人',
  `state` int(11) NOT NULL DEFAULT '1' COMMENT '法人機構當前狀態，0：正常，1：關閉',
  `weight` int(11) DEFAULT '0' COMMENT '權重，當生育量小時，判斷分給誰',
  `spbz` int(11) DEFAULT '0' COMMENT '審批標準，當大於此標誌時，任務掛起，短信通知',
  `jgjc` varchar(50) DEFAULT NULL COMMENT '機構簡稱',
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=gbk AUTO_INCREMENT=121 ;

--
-- 轉存表中的數據 `frjg`
--

INSERT INTO `frjg` (`id`, `jgbh`, `jgmc`, `jgm`, `htqssj`, `htyxsj`, `dxfsl`, `dxsyl`, `mbkhl`, `cjsj`, `lastactive`, `xmmc`, `cjr`, `state`, `weight`, `spbz`, `jgjc`) VALUES
(1, '001', '省管理中心', '27000099', '2012-08-29', '2014-09-01', 200000, 200000, 10000, '2012-07-26 00:00:00', '2012-08-08 15:38:00', 'test2', 'zichen', 0, 0, 0, NULL),
(2, '002', '臨渭區聯社管理中心', '27050199', '2012-08-29', '2014-09-01', 200000, 199973, 10000, '2012-07-26 00:00:00', '2012-08-08 15:38:00', 'test2', 'zichen', 0, 0, 0, NULL),
(3, '003', '新城區聯社管理中心', '27011399', '2012-08-29', '2014-09-01', 200000, 199954, 10000, '2012-07-26 00:00:00', '2012-08-08 15:38:00', 'test2', 'zichen', 0, 0, 0, NULL),
(4, '004', '碑林區聯社管理中心', '27010199', '2012-08-29', '2014-09-01', 200000, 199977, 10000, '2012-07-26 00:00:00', '2012-08-08 15:38:00', 'test2', 'zichen', 0, 0, 0, NULL),
(5, '005', '灞橋聯社管理中心', '27010499', '2012-08-29', '2014-09-01', 200000, 199975, 10000, '2012-07-26 00:00:00', '2012-08-08 15:38:00', 'test2', 'zichen', 0, 0, 0, NULL),
(6, '006', '雁塔聯社管理中心', '27010299', '2012-08-29', '2014-09-01', 200000, 199871, 10000, '2012-07-26 00:00:00', '2012-08-08 15:38:00', 'test2', 'zichen', 0, 0, 0, NULL),
(7, '007', '未央區聯社管理中心', '27010399', '2012-08-29', '2014-09-01', 200000, 199928, 10000, '2012-07-26 00:00:00', '2012-08-08 15:38:00', 'test2', 'zichen', 0, 0, 0, NULL),
(8, '008', '蓮湖聯社管理中心', '27010599', '2012-08-29', '2014-09-01', 200000, 199960, 10000, '2012-07-26 00:00:00', '2012-08-08 15:38:00', 'test2', 'zichen', 0, 0, 0, NULL),
(9, '009', '臨潼聯社管理中心', '27010699', '2012-08-29', '2014-09-01', 200000, 199990, 10000, '2012-07-26 00:00:00', '2012-08-08 15:38:00', 'test2', 'zichen', 0, 0, 0, NULL),
(10, '010', '西安市閻良區聯社管理中心', '27010799', '2012-08-29', '2014-09-01', 200000, 199978, 10000, '2012-07-26 00:00:00', '2012-08-08 15:38:00', 'test2', 'zichen', 0, 0, 0, NULL),
(11, '011', '長安區信用聯社管理中心', '27010899', '2012-08-29', '2014-09-01', 200000, 199956, 10000, '2012-07-26 00:00:00', '2012-08-08 15:38:00', 'test2', 'zichen', 0, 0, 0, NULL),
(12, '012', '周至聯社管理中心', '27011099', '2012-08-29', '2014-09-01', 200000, 199995, 10000, '2012-07-26 00:00:00', '2012-08-08 15:38:00', 'test2', 'zichen', 0, 0, 0, NULL),
(13, '013', '高陵聯社管理中心', '27011199', '2012-08-29', '2014-09-01', 200000, 199985, 10000, '2012-07-26 00:00:00', '2012-08-08 15:38:00', 'test2', 'zichen', 0, 0, 0, NULL),
(14, '014', '藍田聯社管理中心', '27011299', '2012-08-29', '2014-09-01', 200000, 199949, 10000, '2012-07-26 00:00:00', '2012-08-08 15:38:00', 'test2', 'zichen', 0, 0, 0, NULL),
(15, '015', '戶縣管理中心', '27010999', '2012-08-29', '2014-09-01', 200000, 199987, 10000, '2012-07-26 00:00:00', '2012-08-08 15:38:00', 'test2', 'zichen', 0, 0, 0, NULL),
(16, '016', '金臺區信用聯社管理中心', '27030299', '2012-08-29', '2014-09-01', 200000, 199957, 10000, '2012-07-26 00:00:00', '2012-08-08 15:38:00', 'test2', 'zichen', 0, 0, 0, NULL),
(17, '017', '渭濱信用聯社管理中心', '27030199', '2012-08-29', '2014-09-01', 200000, 199981, 10000, '2012-07-26 00:00:00', '2012-08-08 15:38:00', 'test2', 'zichen', 0, 0, 0, NULL),
(18, '018', '咸陽市渭城區聯社管理中心', '27040299', '2012-08-29', '2014-09-01', 200000, 199987, 10000, '2012-07-26 00:00:00', '2012-08-08 15:38:00', 'test2', 'zichen', 0, 0, 0, NULL),
(19, '019', '咸陽市秦都區聯社管理中心', '27040199', '2012-08-29', '2014-09-01', 200000, 199979, 10000, '2012-07-26 00:00:00', '2012-08-08 15:38:00', 'test2', 'zichen', 0, 0, 0, NULL);

需求如下：需要將表記錄中各自的 jgmc 字段值賦給各自的 jgjc 

2.解決辦法：

錯誤實現方法：

update frjg set frjg.jgjc=(select jgmc from frjg f where  f.id=frjg.id ) where  1

執行SQL命令，報錯。錯誤信息爲

#1093 - You can't specify target table 'frjg' for update in FROM clause

正確實現方法，需要建立一張中間表，中間表的內容和frjg表完全相同，之後進行修改frjg表，中間和frjg表之間存在“主外鍵關係”（並不存在這種關係）：

create table tmp as (select * FROM frjg WHERE 1 );
update frjg SET jgjc = (SELECT jgmc FROM tmp WHERE frjg.id=tmp.id ) WHERE 1;
drop table tmp;

 

 上邊的方法是可以實現的，但對於上述問題，還有一種更簡單的解決辦法，一條sql語句搞定（上述方法可以誤導了大家，灰常抱歉，現在改正錯誤） ：

   update frjg  SET jgjc = jgmc   WHERE 1;