摘要:
1.PRIMARY KEY(主键索引) mysql>ALTER TABLE `table_name` ADD PRIMARY KEY ( `column` ) 2.UNIQUE(唯一索引) mysql>ALTER TABLE `table_name` ADD UNIQUE (`column` ) 3 阅读全文
摘要:
UPDATE table_a aLEFT JOINtable_b bON p.id= a.uidSET a.name = b.nameWHERE a.name != '' 阅读全文