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Oracle中的臨時(shí)表用法匯總
瀏覽:2日期:2023-11-14 17:28:31
說明:下文中的一些說明和示例代碼摘自CSDN,恕不一一指明出處,在此一并對相關(guān)作者表示感謝! 假如作者有異議,請來信說明1 語法;在Oracle中,可以創(chuàng)建以下兩種臨時(shí)表: 1) 會(huì)話特有的臨時(shí)表 CREATE GLOBAL TEMPORARY <TABLE_NAME> (<column specification> ) ON COMMIT PRESERVE ROWS; 2) 事務(wù)特有的臨時(shí)表 CREATE GLOBAL TEMPORARY <TABLE_NAME> (<column specification> ) ON COMMIT DELETE ROWS; CREATE GLOBAL TEMPORARY TABLE MyTempTable 所建的臨時(shí)表雖然是存在的,但是假如insert 一條記錄然后用別的連接登上去select,記錄是空的。--ON COMMIT DELETE ROWS 說明臨時(shí)表是事務(wù)指定,每次提交后ORACLE將截?cái)啾恚▌h除全部行) --ON COMMIT PRESERVE ROWS 說明臨時(shí)表是會(huì)話指定,當(dāng)中斷會(huì)話時(shí)ORACLE將截?cái)啾怼? 動(dòng)態(tài)創(chuàng)建;create or replace procedure pro_temp(v_col1 varchar2,v_col2 varchar2) asv_num number;beginselect count(*) into v_num from user_tables where table_name='T_TEMP';--create temporary tableif v_num<1 thenexecute immediate 'CREATE GLOBAL TEMPORARY TABLE T_TEMP (COL1 VARCHAR2(10),COL2 VARCHAR2(10)) ON COMMIT delete ROWS';end if;--insert dataexecute immediate 'insert into t_temp values('''v_col1''','''v_col2''')';execute immediate 'select col1 from t_temp' into v_num;dbms_output.put_line(v_num);execute immediate 'delete from t_temp';commit;execute immediate 'drop table t_temp';end pro_temp;測試:15:23:54 SQL> set serveroutput on15:24:01 SQL> exec pro_temp('11','22');11PL/SQL 過程已成功完成。已用時(shí)間: 00: 00: 00.7915:24:08 SQL> desc t_temp;ERROR:ORA-04043: 對象 t_temp 不存在3 特性和性能(與普通表和視圖的比較);臨時(shí)表只在當(dāng)前連接內(nèi)有效臨時(shí)表不建立索引,所以假如數(shù)據(jù)量比較大或進(jìn)行多次查詢時(shí),不推薦使用數(shù)據(jù)處理比較復(fù)雜的時(shí)候時(shí)表快,反之視圖快點(diǎn)在僅僅查詢數(shù)據(jù)的時(shí)候建議用游標(biāo): open cursor for 'sql clause';歡迎補(bǔ)充!
標(biāo)簽:
Oracle
數(shù)據(jù)庫
排行榜
