create table a( no number notnull, name varchar(10) notnull, loc varchar(10) notnull); create table b( no number notnull, name varchar(10) notnull, loc varchar(10) notnull); insert into a values(10,
SQL> select process,status from v$managed_standby;PROCESS STATUS--------- ------------ARCH CONNECTEDARCH ERRORRFS IDLERFS IDLE查看parameter,發現log_archive_dest_state_2設定ENABLE。由於不做SWITCH OVER,所以,這個參數對於我的DG來說,是沒用的。於是:alter system set
Chapter 1 Meet HadoopData is large, the transfer speed is not improved much. It's a long time to read all data from one single disk - writing is even more slow. The obvious way to reduce the time is read from multiple disk once.The first problem
第十一章:使用資料處理函數 Like almost any other computer language, SQL supports the use of functions to manipulate data. Functions are operations usually performed on data, usually to facilitate conversion and manipulation.
1、啟動編輯器$ vi file_name如果檔案存在即可開啟該檔案,否則建立一個新的檔案。2、vi 編輯器的狀態vi 編輯器有兩種狀態:1)命令狀態可輸入各種指令,以實現 vi 的編輯功能或設定 vi 的環境2)文字輸入狀態可直接進行文字操作用 vi 開啟或建立一個新檔案之後便首先處於命令狀態。3、使用
http://boylook.itpub.net/post/43144/520538在OCP SQL部分有這樣一道題:You need to add a NOT NULL constraint to the QUANTITY column in the PO_DETAIL table. Which statement should you use to complete this task?正確 A. ALTER TABLE po_detail MODIFY (quantity NOT