Posted by J.O. Aho on 01/09/06 18:02

jj wrote:
> Hi all
>
> All of a sudden I cant alter values in rows where the column is a primary
> key. It just reverts to the old value that was there if I try to make any
> changes.
>
> If I try changing a value on any other (non-primary key) column , it changes
> the data no problem.


Control that the value you change to aren't already in the table

eg table Simple
Id Name
A Carl
B Buddy
C Cheng
D David
E Earl

ID is the primary key.

UPDATE Simple SET Id='C' WHERE Id='A';

This will fail as there already is a row with the Id=C (Cheng) and with the
primary key there is only allowed to be one of each.

While the Name isn't a primary key, you could do

UPDATE Simple SET Name='Cheng' WHERE Id='A';

As there aren't any restrictions.


//Aho

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