解决mysql 修改表记录 1093错误
1.需求 ：
已知表信息如下 ：
表名 ：frjg
表结构：
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 '法人机构编号', `jgmc` varchar(50) CHARACTER SET utf8 NOT NULL COMMENT '机构名称', `jgm` varchar(8) CHARACTER SET utf8 NOT NULL COMMENT '机构码', `htqssj` date NOT NULL COMMENT '合同起始时间', `htyxsj` date NOT NULL COMMENT '合同有效时间', `dxfsl` int(11) NOT NULL COMMENT '短信发送总量', `dxsyl` int(11) NOT NULL COMMENT '短信剩余量', `mbkhl` int(11) NOT NULL COMMENT '目标客户量', `cjsj` datetime NOT NULL COMMENT '创建时间', `lastactive` datetime NOT NULL COMMENT '最后一次操作时间', `xmmc` varchar(50) CHARACTER SET utf8 NOT NULL COMMENT '项目名称', `cjr` varchar(50) CHARACTER SET utf8 DEFAULT NULL COMMENT '创建人', `state` int(11) NOT NULL DEFAULT '1' COMMENT '法人机构当前状态，0：正常，1：关闭', `weight` int(11) DEFAULT '0' COMMENT '权重，当生育量小时，判断分给谁', `spbz` int(11) DEFAULT '0' COMMENT '审批标准，当大于此标志时，任务挂起，短信通知', `jgjc` varchar(50) DEFAULT NULL COMMENT '机构简称', PRIMARY KEY (`id`)) ENGINE=MyISAM DEFAULT CHARSET=gbk AUTO_INCREMENT=121 ;---- 转存表中的数据 `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', '临渭区联社管理中心', '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', '新城区联社管理中心', '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', '碑林区联社管理中心', '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', '灞桥联社管理中心', '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', '雁塔联社管理中心', '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', '未央区联社管理中心', '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', '莲湖联社管理中心', '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', '临潼联社管理中心', '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', '西安市阎良区联社管理中心', '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', '长安区信用联社管理中心', '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', '周至联社管理中心', '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', '高陵联社管理中心', '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', '蓝田联社管理中心', '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', '户县管理中心', '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', '金台区信用联社管理中心', '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', '渭滨信用联社管理中心', '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', '咸阳市渭城区联社管理中心', '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', '咸阳市秦都区联社管理中心', '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：需要将表记录中各自的 jgmc 字段值赋给各自的 jgjc
2.解决办法：
错误实现方法：
update frjg set frjg.jgjc=(select jgmc from frjg f where f.id=frjg.id ) where 1
执行SQL命令，报错。错误信息为
#1093 - You can't specify target table 'frjg' for update in FROM clause
正确实现方法，需要建立一张中间表，中间表的内容和frjg表完全相同，之后进行修改frjg表，中间和frjg表之间存在“主外键关系”（并不存在这种关系）：
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;
