Null date is displaying as 01/01/0001 in code behind of ASP.Net page

Question

i am fetching the date by below code from db using c# ,how to check null date .when date is null then it shows default date on page 01/01/0001

IssueDate = dataReader.GetValue<DateTime>(DbColumnNames.PLAST_ISSUE_DT)

If you want to be able to check for null values, you need to use a nullable type. See duplicates. — Peter Duniho, Jun 03 '21 at 21:34
@GuruStron - your comment is the exact answer of my issue.thx — vim, Jun 03 '21 at 21:52

score 3 · Answer 1 · answered Jun 03 '21 at 21:11

3

DateTime is not a refence type, so it cannot be null. You can use a nullable date with DateTime? (which is the same as Nullable<DateTime>) to check for null value.

DateTime? issueDate = dataReader.GetValue<DateTime?>(DbColumnNames.PLAST_ISSUE_DT);

if (issueDate == null) {
    // Is null
}

Or check for the default value of DateTime, which should be 01/01/0001.

DateTime issueDate = dataReader.GetValue<DateTime>(DbColumnNames.PLAST_ISSUE_DT);

if (issueDate == default) {
    // Is default value
}

answered Jun 03 '21 at 21:11

Jossean Yamil

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`DateTime is not a refence type, so it cannot be null.` A minor quibble, but `DateTime?` is _also_ not a reference type (which is why I wouldn't mention that explicitly - it just confuses the issue). Perhaps it would be clearer to say that `DateTime` cannot have the value `null`? – mjwills Jun 03 '21 at 22:26
@mjwills I never said that `DateTime?` is a reference type. – Jossean Yamil Mar 25 '22 at 21:45
You never _said_ it, but your argument strongly _implies_ it. You say "X is not Y, you need to use Z instead". At the very least you _imply_ that Z is Y (which, in this case, it isn't) - hence why I said it was best not to argue it in that way. In other words, by saying "DateTime is not a refence type, so it cannot be null" it introduces confusion - since you are suggesting using `DateTime?` which _also_ is not a reference type. So the person reading the answer will be confused. Why does `DateTime?` work even if it isn't a reference type? Hence why I suggested the specific wording that I did. – mjwills Mar 27 '22 at 01:53

score 1 · Answer 2 · answered Jun 03 '21 at 21:11

DateTime is a value type so it always evaluates to something. Likewise, if you don't put a value in an int the value inside will be 0 and not null.

If you do want to have null then you have to make your database field nullable and use a define IssueDate as type DateTime? which is Nullable of DateTime and it will be able to hold the null value.

Null date is displaying as 01/01/0001 in code behind of ASP.Net page

2 Answers2