LINQ query C# ASP.NET

Question

String check = Data.Logins.Where(Login=>Login.Username==TextBoxnewusername.Text) I have a table named Login. There are 4 columns - Username password Name Address. The Username column is of data type nvarchar(max). The 'TextBoxnewusername.Text' is a textbox where new users input their user name. Now the error is as follows- Cannot implicitly convert type 'system.linq.IQueryable ' to 'String'. Any idea how to correct it?? Is there any casting it?

Nigel Fernandes · Answer

Add Any at end and change string check to bool check. Data.Logins.Where(Login=>Login.Username==TextBoxnewusername.Text).Any()

Sayan Chatterjee · Answer

Adding .any() and changing to bool is correct syntax wise. Thanks! However the issue is not resolved. I'm trying to verify whether a new user while sign-up already exists in the database ('Login' table). Below is the code that I have written. However it's not checking the 'textboxnewusername.Text' with the existing 'Username' in the 'Login table'. Any idea what to do? The 'Labelmessage' is not displayed in any case! protected void Buttonsubmit_Click(object sender EventArgs e) { using (ShopDataContext Data = new ShopDataContext()) { Login newlogin = new Login(); //Creating instance of the 'Login' table// var check = Data.Logins.Where(Login => Login.Username==TextBoxnewusername.Text); //Lambda expression// foreach (Login output in check) { if (output.Username != TextBoxnewusername.Text) { newlogin.Name = TextBoxname.Text; newlogin.Username = TextBoxnewusername.Text; newlogin.Address = TextBoxaddress.Text; newlogin.password = TextBoxnewpassword.Text; Data.Logins.InsertOnSubmit(newlogin); Data.SubmitChanges(); Labelmessage.Text = Successful; } else { Labelmessage.Text = User name already exists in the database pls. select a new username; } } } }

Rijwan Ansari · Answer

You should to use FirstOrDefault or SingleOrDefault

Gnanavel Sekar · Answer

Hi sayan var result=( from u in Data.Logins where u. Username .Any(c => c. Username == TextBoxnewusername.Text ) select u); Or var result=Data.Logins.Where(Login=>Login.Username==TextBoxnewusername.Text).Any();

Rajkiran Swain · Answer

https://www.codeproject.com/Questions/716796/Cannot-implicitly-convert-type-System-Linq-IQuerya

D Donthu · Answer

Both value convert to string format

LINQ query C#, ASP.NET