句用复制show databases;   show tables from db_name;   show columns from table_name from db_name;   show index from talbe_name [from db_name];   show status;   show variables;   show [full] processlist;   show table status [from db_name];   show grants for user;   1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.