DB2建备份表和清空表

soyizi

　　DB2跟ORACLE还是挺大的区别的.习惯了用ORACLE.用起DB2,觉得简直不可理喻.但是,实际上.DB2是很强大的.不过.这些可不是我要讨论的问题.现在.来看看DB2下ORACLE的一些命令如何实现.
　　1.DB2下CREATE TABLE TableName AS
　　前几天.用DB2,有一批数据.想创建数据的备份表.习惯性的用上了CREATE TABLE AS.提示
　　DB21034E The command was processed as an SQL statement because it was not a
valid Command Line Processor command. During SQL processing it returned:
SQL0104N An unexpected token "create table kf2.tbl as" was found following
"BEGIN-OF-STATEMENT". Expected tokens may include: "<space>".
SQLSTATE=42601
　　一看傻眼了.马上找资料.花了不少时间.才发现.DB2不可以这样操作..郁闷到了.不过.可以用以下的方法:
　　先建表,再插数据.
　　create table TableName as (select * from TblName) definition only;
　　按原表的字段建个表.还好不用去查表的字段再慢慢敲建表的SQL..
　　然后.插数据就简单了.
　　insert into TableName select * from TblName;
　　用惯了CREATE TABLE AS的友友们是不是觉得很不爽啊?没办法..这是DB2..
　　2. DB2下的TRUNCATE TABLE
　　今天对一个临时表插完数据后才发现.数据插错了-。-要清表.习惯性的动作又来了.TRUNCATE TABLE.嗯.不用想了.又失败了.咋办捏.因为是省电信级别的用户数据.动不动就几百万的.DELETE FROM TABLE?我死你看..好吧..又是浪费大脑细胞的SEARCH IN BAIDU..最后发现.竟然是用IMPORT来代替了..
　　这方法简单了.
　　VI NULL.DAT
　　不用添加数据.直接保存,退出
　　然后执行
　　db2 "import from NULL.DAT of del replace into TABLENAME"
　　出现了:
　　SQL3109N The utility is beginning to load data from file "NULL.DAT".
　　SQL3110N The utility has completed processing. "0" rows were read from the
input file.
　　SQL3221W ...Begin COMMIT WORK. Input Record Count = "0".
　　SQL3222W ...COMMIT of any database changes was successful.
　　SQL3149N "0" rows were processed from the input file. "0" rows were
successfully inserted into the table. "0" rows were rejected.
　　
Number of rows read = 0
Number of rows skipped = 0
Number of rows inserted = 0
Number of rows updated = 0
Number of rows rejected = 0
Number of rows committed = 0
　　OK.完成了TRUNCATE TABLE的功能.虽然麻烦了点.总比你DELETE FROM TABLE快多了吧.