CODEWITHSUNDEEP
vb.net
Charles
Charles

Reputation: 189

VB.net application using reader HasRows

I am running an SQL Query with data readers in vb.net

reader3 = myCommand3.ExecuteReader
reader3.Read()
If reader3.HasRows Then
    FromToDates = reader3.GetString(3)
End If

There are no rows being returned in this particular query, however even though the if reader3.HasRows is being used its still showing an error saying:

Additional information: Data is Null. This method or property cannot be called on Null values.

this is when trying to set the FromToDates variable but there are no rows being returned so it should not even reach this part

Upvotes: 0

Views: 6810

Answers (3)

roflplanes
roflplanes

Reputation: 73

It seems that even though the row is empty (all DBNull, perhaps), there IS a row object returning from the query. There are several different solutions presented in this thread that all take differing approaches to catching the empty row before it errors!

http://www.vbforums.com/showthread.php?555183-datareader-and-empty-records

Upvotes: 0

Tim Schmelter
Tim Schmelter

Reputation: 460048

I doubt that there are no rows, i assume that there is at least one row where the value is NULL. You could check it with the IsDBNull-method:

If reader3.HasRows AndAlso Not reader3.IsDbNull(3)  Then
    FromToDates = reader3.GetString(3)
End If

However, the variable name suggests that it's a date, but you are storing it as string. Use the correct type which is date or datetime. If it's actually a datetime use:

Dim FromToDates As Date 
If reader3.HasRows AndAlso Not reader3.IsDbNull(3)  Then
    FromToDates = reader3.GetDateTime(3)
End If

Upvotes: 2

I kiet
I kiet

Reputation: 174

if you are using Reader.read() then i don't think so you need reader,hasrow(). you can do somthing like this

reader3 = myCommand3.ExecuteReader
If reader3.Read()Then
FromToDates = reader3.GetString(3)
End If

and related to your error its look like you are getting NULL value from database and in vb you can not read NULL, i will suggest to use ISNULL(Column_NAME,'') function in your SQL Script.

Upvotes: 0

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