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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Specifying column datatypes in CTAS
Something like this with the CAST operator may work for you:
SQL> create table t1 (
2 col1 varchar2(100)
3 );
Table created.
SQL> insert into t1 values ('100');
1 create table t2 as
2* select CAST( col1 AS varchar2(50)) col1 from t1
SQL> /
Table created.
SQL> desc t2;
Name Null? Type -------------------------------------- -------- ---------------------------- COL1 VARCHAR2(50)
SQL> select * from t2;
COL1
Justin Cave
Distributed Database Consulting, Inc.
http://www.ddbcinc.com
-----Original Message-----
From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Mark Richard
Sent: Tuesday, February 24, 2004 4:00 PM
To: oracle-l_at_freelists.org
Subject: Specifying column datatypes in CTAS
Hi List,
I have stumbled across a problem and I am hoping there is an easy solution. I have to add two columns to an existing table. One of these columns is populated with a constant value for all existing records and the other can be determined using a simple DECODE on other existing columns.
The table is quite large (~100 million records) and I was hoping to combine the activity with a rebuild into a new tablespace at the same time. Therefore, I figure the quickest way to achieve this is a simple "create table as select" type statement.
My problem is specifying the datatypes, and in particular the NOT NULL state of the newly added columns. Working on Oracle 8.1.7.4 I get an error if I try something like "create table my_dual (the_col varchar2(10) not null) as select * from dual" - I cannot specify datatypes when using an "as select..." clause it seems.
I realise I can name the new columns using column aliasing in the select clause, but I am struggling to get the length of the data type and the NOT NULL attribute set on the new columns.
What is the best way to resolve this problem? Is there some syntax I am missing or do I absolutely need to create structure and then insert data?
Thanks in advance,
Mark.
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-- Archives are at http://www.freelists.org/archives/oracle-l/ FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html ----------------------------------------------------------------- ---------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ---------------------------------------------------------------- To unsubscribe send email to: oracle-l-request_at_freelists.org put 'unsubscribe' in the subject line. -- Archives are at http://www.freelists.org/archives/oracle-l/ FAQ is at http://www.freelists.org/help/fom-serve/cache/1.html -----------------------------------------------------------------Received on Tue Feb 24 2004 - 17:06:19 CST
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