How to check if I have the username in database C#? -

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• check if record in table exist in database through executenonquery 5 answers

i'm new in c# , databases. made database in add data person. actually, data person create account. checked if email have email structure , checked if password same retype password. here have code:

if (pass.text != rpass.text)         {             messagebox.show("password don't match!");             return;         }         string emailcheck = email.text;          bool valid = false;         int count_dot = 0;          (int = 0; < emailcheck.length; i++)             if (emailcheck[i] == '@') valid = true;             else if (emailcheck[i] == '.') count_dot++;          if (valid == false || count_dot == 0)         {             messagebox.show("invalid email!");             return;         }         con = new sqlconnection(@"data source=maria-pc;initial catalog=account;integrated security=true");         con.open();         cmd = new sqlcommand("insert [dbo].[cont1] (username,password,first_name,last_name,birth_year,email,work_type) values (@username,@password,@first_name,@last_name,@birth_year,@email,@work_type)", con);         cmd.parameters.add("@username", username.text);         cmd.parameters.add("@password", password.text);         cmd.parameters.add("@first_name", first_name.text);         cmd.parameters.add("@last_name", last_name.text);         cmd.parameters.add("@birth_year", datetime.parse(birth_year.text));         cmd.parameters.add("@email", email.text);         cmd.parameters.add("@work_type", work_tpye.selecteditem.tostring());         cmd.executenonquery();          con.close(); 

so, want check, before add in database, if have username in database. have idea have do, don't know how do.

have @ merge command. there many other tutorials on web.