SQLDataReader Null to datetime

Question

Having an issue with casting a datetime from a reader where the value is null.

form._date101 = reader[52] == DBNull.Value ? DBNull.Value : (DateTime?)reader[52];

getting: Type of conditional expression cannot be determined because there is no implicit conversion between 'System.DBNull' and 'System.DateTime?'

any ideas?

You could probably discombobulate yourself if you broke that into two lines. — user195488
– user195488, Commented May 9, 2013 at 19:50
The two expressions which can be returned must be the same type. Your first possibility is returning a DBNull type, and the next is returning a DateTime? type. — Jasmine
– Jasmine, Commented May 9, 2013 at 20:13

Jon Skeet · Accepted Answer · 2013-05-09 19:48:53Z

12

I suspect you meant:

form._date101 = reader[52] == DBNull.Value ? null : (DateTime?)reader[52];

That's assuming that _date101 is a field of type DateTime?. I expect you want to say "Use the null value of DateTime? if the value was null in the database; otherwise use the non-null value.

answered May 9, 2013 at 19:48

Jon Skeet

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KyleMit · Accepted Answer · 2020-08-26 04:56:20Z

2

You can also take Jon's answer and add it as an extension method like this:

public static class ReaderExtensions
{
    public static DateTime? GetNullableDateTime(this SqlDataReader reader, string name) =>
        reader[name] == DBNull.Value ? (DateTime?)null : (DateTime?)reader[name];
}

Then you can use it like this:

item.PatientDob = reader.GetNullableDateTime("Birth_Dt");

answered Aug 26, 2020 at 4:56

KyleMit♦

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