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
}
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).