在create table的语句中,key和index混淆在一起,官方手册中的解释是这样: KEY is normally a synonym for INDEX. The key attribute PRIMARY KEY can also be specified as just KEY when given in a column definition. This was implemented for compatibility with other database systems.
SQL SELECT INTO 语句可用于创建表的备份复件.SELECT INTO 语句SELECT INTO 语句从一个表中选取数据,然后把数据插入另一个表中.SELECT INTO 语句常用于创建表的备份复件或者用于对记录进行存档. SQL SELECT INTO 语法 您可以把所有的列插入新表:SELECT *INTO new_table_name [IN externaldatabase] FROM old_tablename或者只把希望的列插入新表:SELECT column_name