查表的复杂用法:
select * from server_name.database_name.table_owner_name.table_name
查表的省略用法:
select * from server_name.database_name.table_owner_name.table_name
其中可省略除table_name以外的其他name,例如:
select * from database_name.table_owner_name.table_name
select * from table_name
select * from server_name.database_name..table_name
select * from server_name...table_name