If DataKeyNames is set to a field not defined as a primary key, then…

Question

Hello,

1) I noticed that if I set GridView.DataKeyNames to a field that actually isn’t defined as primary key in data source, data source control ( or perhaps GridView?) will somehow know that field set in DataKeyNames isn’t really a primary key. I became aware of that fact when I opened Configure the Select Statement window ( via GridView’s Smart Tasks pop up --> Configure Data Source --> Configure the Select Statement window --> Advanced) and window had both radio buttons disabled.

a) So how did Asp.Net “figure it out” that field set in DataKeyNames is not actually a primary key?

b) Also, shouldn’t it be up to programmer to set DataKeyNames to whatever field she chooses to, even if that field is not defined as primary key in a data source?

thanx

Answer 1

Well, the purpose of the DataKeyNames property is to uniquely identify each and every data row in your data set. For that, ASP.NET needs to make 100% sure it's really truly a uniquely identifying column (or set of columns) that you provide, and the only one that can be truly checked is the primary key of a table - this will always be uniquely identifying a row (that's the very definition of a primary key).

I guess that's the reason that ASP.NET insists on the primary key for the DataKeyNames - any other column (or set of columns) can't really be checked for validity - so it's better to refuse them rather than running into the problems if it's not a uniquely identifying key.....

Marc