<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Typ…
mysql中You can't specify target table <tbl> for update in FROM clause错误的意思是说,不能先select出同一表中的某些值,再update这个表(在同一语句中). 如下l: 需要将select出的结果再通过中间表select一遍,就可以规避了错误. 如下: PS:这个问题只出现于mysql,sql service 和 oracle 不会出现此问题.…
use mysql: ALTER TABLE `proc` MODIFY COLUMN `comment` text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL AFTER `sql_mode`; 具体原因请看:http://www.cnblogs.com/jackluo/p/3395147.html…
NSSet and NSDictionary, along with NSArray are the workhorse collection classes of Foundation. Unlike other standard libraries, implementation details are hidden from developers, allowing them to write simple code and trust that it will be (reasonabl…