Question

I have to modify a Visual Studio 2010 C# project that works with Oracle, looking at some code I’ve found a function that returns a List<> with values loaded from a database stored procedure (cursor)

while (myIDataReader.Read())
{
    // OK
    myTable.myStringField = myIDataReader["TableStringField"].ToString();
    // ¿?
    myTable.myIntField =
    Convert.ToInt32((myIDataReader["TableIntField"] == DBNull.Value) ? null : myIDataReader["myTableField"]);
}

Everything’s ok, just want to know, what conditions are given when assign myTable.myIntField, I know this column is nullable, but I don’t get the syntax, if someone can explain I’ll be thankful

Answer 1

You are talking about this line?

myTable.myIntField =
Convert.ToInt32((myIDataReader["TableIntField"] == DBNull.Value) ? null : myIDataReader["myTableField"]);

If you break that statement apart, you have a type of conditional, often called the Ternary operator, explained here.

conditional ? if_true_do_this : if_false_do_this

It is really just a different syntax for:

if(conditional) {
    if_true_do_this;
} else {
    if_false_do_this
}

After that, it simply passes the result to Convert.ToInt32() to turn it from a string into an int.

So that line of code is just a more concise version of this:

if(myIDataReader["TableIntField"] == DBNull.Value)
{
    myTable.myIntField = Convert.ToInt32(null);
}
else
{
    myTable.myIntField = Convert.ToInt32(myIDataReader["myTableField"]);
}