How can I make a Select using Entity Framework , and check if the registry exists?
Example:
txtlogin.text
txtsenha.text
Login table.
valida() class created to execute the command and selecting valida() it will check if usuario and senha exists via Entity Framework
I use this way:
using(var context = new SeuContexto()){
var Usuario = context.login.firstOrDefault(x=> x.usuario == txtlogin.text && x.senha == txtsenha.text)
if(Usuario != null)
{
//Existe o usuário
}else
{
//Se voltar nulo, não existe o usuário com esta senha
}
}
You can use the Any() method of LINQ. It returns true if there is any ( any in English) record. If it does not exist, it returns false . Ex:
if(contexto.Entidade.Any(x => x.Login == txtLogin.Text && x.Senha == txtSenha.Text))
{
//existe
}
else
{
//não existe
}
The documentation for the Any() method you can see here >.