Constraint unique where other column
Hi,
It's possible to have constrait unique on A column only if otherB column value is null when insert ?
It's possible to have constrait unique on A column only if otherB column value is null when insert ?
GNot sure what you mean by the insert part.
You can have a unique constraint involving two columns but it will apply to the data at any point.
I think this does what you want.
If you try and change column_B later to be NULL when after you have a non-unique condition on column_A then that will fail.
You can have a unique constraint involving two columns but it will apply to the data at any point.
I think this does what you want.
If you try and change column_B later to be NULL when after you have a non-unique condition on column_A then that will fail.
JMaybe i have to change my schema.
I have table : uid, owner_id , temporary?
I want unique constrait onwer_id only if temporary is null.
User A , insert uid10, userA, null = ok
User A , insert uid11, userA, null = database block
User B , insert uid12, userB, true = ok
User B , insert uid13, userB, true = ok
I have table : uid, owner_id , temporary?
I want unique constrait onwer_id only if temporary is null.
User A , insert uid10, userA, null = ok
User A , insert uid11, userA, null = database block
User B , insert uid12, userB, true = ok
User B , insert uid13, userB, true = ok
GI think what I showed does that, but it is pretty messy as you could do null sometimes and true others for the same user....
What it will also do though is:
User A, insert uid12,userA, true = ok
User B, insert uid14,userB, null = block
After you ran your other ones.
What it will also do though is:
User A, insert uid12,userA, true = ok
User B, insert uid14,userB, null = block
After you ran your other ones.
GBut I've not done anything like this so you would need to test it.
And I can't quite wrap my head around what happens for
User A, insert uid12,userA, true...
If you already have the UserA inserted with null....
And I can't quite wrap my head around what happens for
User A, insert uid12,userA, true...
If you already have the UserA inserted with null....
Jyes i see.
i go separate into two table its cleaner
Thank for help
i go separate into two table its cleaner
Thank for help
