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How to change not null column to nullable column

 
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nightbuzzz

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Joined: 04 May 2007
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PostPosted: Tue Nov 18, 2008 9:53 am    Post subject: How to change not null column to nullable column
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I have a column in a table which is not null right now.

I want to change the attribute of that column to NULL.

How can it be done?

Can i use ALTER table command to achieve this?
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Prasanthhere

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Joined: 03 Aug 2005
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PostPosted: Tue Nov 18, 2008 10:44 am    Post subject: Reply to: How to change not null column to nullable column
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Alter command doesn't work for your criteria .

You have to export the data drop the table and recreate the the table with the required column to be null
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Prasanthhere

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PostPosted: Tue Nov 18, 2008 10:51 am    Post subject:
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I f you are using DB2 V9 it can be done through ALTER I guess

Please go through this link

http://publib.boulder.ibm.com/infocenter/db2luw/v9/index.jsp?topic=/com.ibm.db2.udb.admin.doc/doc/r0000888.htm
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Srihari Gonugunta

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PostPosted: Tue Nov 18, 2008 12:07 pm    Post subject:
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You can add a constraint for this.

ALTER TABLE <TABLENAME> ADD CONSTRAINT NULL_FIELD CHECK (<FIELD> IS NOT
NULL)
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dick scherrer

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PostPosted: Tue Nov 18, 2008 10:38 pm    Post subject:
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Hello,

I believe you have posted the way to create a new constraint.

What TS asked for is how to remove this constraint using ALTER (if i understand correctly).

Prasanth has posted the 2 answers - 1 if db2 is prior v9 and 1 if v9 has been installed.
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Srihari Gonugunta

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PostPosted: Wed Nov 19, 2008 11:19 am    Post subject:
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Dick,
You are right. But I am asking him to add a constraint to check for NULLs, which will avoid dropping and creating the table once again.
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dick scherrer

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PostPosted: Wed Nov 19, 2008 8:30 pm    Post subject:
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Hello Srihari,

Quote:
But I am asking him to add a constraint to check for NULLs
I believe that is what is already defined and the requirement is to remove it.

I may be mistaken and we haven't heard from TS since the question was asked. . .
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Srihari Gonugunta

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PostPosted: Thu Nov 20, 2008 11:12 am    Post subject:
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Hi,
Please ignore my post. Actually, TS wanted to make a NOT NULL column to NULLABLE. My solution is to make a NULLABLE column to NOT NULL.
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ashok_uddaraju

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PostPosted: Thu Nov 20, 2008 1:46 pm    Post subject:
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Yes alter can be used for this change
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dick scherrer

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PostPosted: Fri Nov 21, 2008 12:40 am    Post subject:
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Hello,

Quote:
Yes alter can be used for this change
But only if the system is currently running v9. . . .?

Many (maybe most) systems are not yet running v9. . .
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enrico-sorichetti

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Joined: 14 Mar 2007
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Location: italy

PostPosted: Fri Nov 21, 2008 12:45 am    Post subject: Reply to: How to change not null column to nullable column
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and anyway regardless of the db2 level,
altering on the fly a DB2 table might be acceptable in test..

NEVER IN PRODUCTION
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