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Chidi Okeh
Chidi Okeh

Reputation: 1557

how do I compare two dates?

We would like to compare a date from the db with current date.

Here is what I have tried so far:

'Obtain current date 

Dim curdate As String = Now.ToString("yyyy")

'Now compare curdate with date from db called eventdate. Event date is of dateTime datatype.

If drv("eventdate").ToString = "" And Year(drv("eventdate").ToString) = curdate Then

 'Then do some processing
End if

When I run this code, I get following error:

Conversion from string "" to type 'Date' is not valid.

Please help!

Thank you very much experts.

Upvotes: 1

Views: 863

Answers (3)

jmoreno
jmoreno

Reputation: 13551

I believe you have either a null or empty value, also your comparisn is wrong, try:

If drv("eventdate").ToString <> "" Andalso Year(drv("eventdate").ToString) = curdate Then

 'Then do some processing
End if

Upvotes: 0

KV Prajapati
KV Prajapati

Reputation: 94625

If drv has an instance of DataReader then verify DBNull.

IF Not drv.IsDBNull(column_index_of_eventdate) Then
   ...
   If drv.GetDateTime(column_index).Year=Date.Now.Year Then
        ...
   End If
End If

Upvotes: 1

Joel Coehoorn
Joel Coehoorn

Reputation: 415600

If Today.CompareTo(CDate(drv("eventdate")).Date) = 0 Then
    'Do something
End If

I'm making the assumption here that you only care about the day, and not the time. Otherwise, the odds of having a match within a given day would be about 1 in 2.5 million.

Based on the comment:

If Today.Year.CompareTo(CDate(drv("eventdate")).Year) = 0 Then
    'Do something
End If

or

If Today.Year = CDate(drv("eventdate")).Year Then
    'Do something
End if

And one more thing: it really sounds like this is a check that should be done by your database. Make it part of the query that returns the results. This will be much faster, and it's where that kind of check belongs. All you'd need is add a check to your where clause like so:

Year(eventdate) = Year(current_timestamp)

Upvotes: 3

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