總覽show 語句 show tables from database_name; -- 顯示當前數據庫中所有表的名稱。?
show databases; -- 顯示mysql中所有數據庫的名稱。?
show columns from database_name.table_name; -- 顯示表中列名稱。?
show grants for user_name; -- 顯示一個用戶的權限,顯示
最大值:select max(num) from table第二大值:select max(num) from table where num not in(select max(num) from table)第三大值:select max(num) from table where num not in(select max(num) from table where num not in(select max(num) from tab