Int32.TryParse() or (int?)command.ExecuteScalar()

Question

I have a SQL query which returns only one field - an ID of type INT.

And I have to use it as integer in C# code.

Which way is faster and uses less memory?

int id;
if(Int32.TryParse(command.ExecuteScalar().ToString(), out id))
{
  // use id
}

or

int? id = (int?)command.ExecuteScalar();
if(id.HasValue)
{
  // use id.Value
}

or

int? id = command.ExecuteScalar() as int?;
if(id.HasValue)
{
  // use id.Value
}

Answer 1

The difference between the three performance wise is negligible. The bottleneck is moving the data from the DB to your app, not a trivial cast or method call.

I would go with:

int? id = (int?)command.ExecuteScalar();
if(id.HasValue)
{
  // use id.Value
}

It fails earlier, if one day people change the command to return a string or a date, at least it will crash and you will have a chance to fix it.

I would also just go with a simple int cast IF I always expected the command to return a single result.

Note, I usually prefer returning an out param than doing the execute scalar, execute scalar feels fragile (the convention that the first column in the first row is a return value does not sit right for me).