[ http://issues.apache.org/jira/browse/DERBY-119?page=all ]

Bryan Pendleton updated DERBY-119:
----------------------------------

    Attachment: alterColumnNotNull_v3.diff

Hi Deepa, thanks for re-reviewing the patch. I think your idea about renaming 
the 
SQLState constant is a good one. Attached is alterColumnNotNull_v3.diff, which
 differs from alterColumnNotNull_v2.diff in that it renames 
      LANG_MODIFY_COLUMN_PKEY_CONSTRAINT
to
     LANG_MODIFY_COLUMN_EXISTING_CONSTRAINT


> Add ALTER TABLE option to change column from NULL to NOT NULL
> -------------------------------------------------------------
>
>                 Key: DERBY-119
>                 URL: http://issues.apache.org/jira/browse/DERBY-119
>             Project: Derby
>          Issue Type: New Feature
>          Components: SQL
>            Reporter: Bernd Ruehlicke
>         Assigned To: Bryan Pendleton
>         Attachments: alterColumnNotNull_1.diff, alterColumnNotNull_v2.diff, 
> alterColumnNotNull_v3.diff
>
>
> There was a thread about this on the Cloudscape forum
> http://www-106.ibm.com/developerworks/forums/dw_thread.jsp?message=4103269&cat=19&thread=59941&forum=370#4103269
> Since this describes the problem I will just copy the content of this entry 
> as my dexscription
> The content of this was 
> "
> Hi,
> I stumbled across a behaviour of cloudscape which is not a bug but IMHO an 
> implementation choice. To assign a primary key to a table using ALTER TABLE 
> all columns must be declared NOT NULL first, which can only be specified upon 
> column creation (no ALTER TABLE statement exists to change the NOT NULL 
> property of a column).
> Most databases I know do two things differently:
> 1) when a primary key is assigned all pk columns are automatically set to NOT 
> NULL, if one of them contains NULL values, the ALTER TABLE statement fails
> 2) it is possible to alter the column to set the NOT NULL property after 
> column creation (fails when there are already records containing NULL values)
> If I have understood the limitations correctly in Cloudscape I have no choice 
> but to remove and re-add the column which is supposed to be used in the 
> primary key, if it is not already declared as NOT NULL. This means that in 
> the case of a table containing valid data (unique and not null) in the column 
> in all records, I would have to export the data, remove and re-add the column 
> and reimport that data, which would not be necessary e.g. in Oracle or MaxDB.
> Is it possible to change that behaviour or is there a good reason for it? It 
> looks as if it makes the life of the user more difficult than necessary for 
> certain metadata manipulations. Making it possible to alter the NOT NULL 
> property of a column would solve this and IMHO having a primary key 
> constraint do this implicitly makes sense as well. 
> Thanks in advance for any insight on this,
> Robert"

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