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Jun 07, 2016 pm 04:10 PM

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临时表让用户只能够操作各自的数据中而互不干扰，不用担心会破坏或影响其他SESSION/TRANSACTION的数据。临时表分为SESSION、TRANSACTION两种。 1. SESSION级的临时表数据在整个SESSION都存在，直到结束此次SESSION； 2. TRANSACTION级的临时表数据在TRANACTION结束后消失，即COMMIT/ROLLBACK或结束SESSION都会清除TRANACTION临时表数据。两种临时表的语法： create global temporary table 临时表名 on commit preserve|delete rows 用preserve时就是SESSION级的临时表，用delete就是TRANSACTION级的临时表一、SESSION级临时表 1、建立临时表 create global temporary table temp_tbl(col_a varchar2(30)) on commit preserve rows 2、插入数据 insert into temp_tbl values('test session table') 3、提交 commit; 4、查询数据 select *from temp_tbl

可以看到数据"test session table'记录还在。结束SESSION，重新登录，再查询数据select *from temp_tbl，这时候记录已不存在，因为系统在结束SESSION时自动清除记录二、TRANSACTION级临时表 1、建立临时表 create global temporary table temp_tbl(col_a varchar2(30)) on commit delete rows； 2、插入数据 insert into temp_tbl values('test transaction table')； 3、提交 commit; 4、查询数据 select *from temp_tbl；

这时候可以看到刚才插入的记录"test transaction table'已不存在了；同样，如果不提交而直接结束SESSION，重新登录记录也不存在

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