how to access user identity in SQL query

[JulieH]

In C# ASP.NET I'm compose a CMS. I want to compose a SQL query that access to my web site user identityIn \[code\]Master Page\[/code\] I have a \[code\]sqlDataSource\[/code\] that I want to compose a sql query that returns an ID from a table. I guess my question was so bad, and you don't understand my questionOK, look at this example: (I write this in my page load)\[code\]sqlDataSource1.SelectCommand = String.Format("select PageGroupID from users where Username = {0};", Page.User.Identity.Name);\[/code\]but it doesn't work please help me... sorry for my bad English typing...