Operator '<>' is not defined for type 'DBNull' and string ""

Question

while using the given below code showing one error. The error is : Operator '<>' is not defined for type 'DBNull' and string "". Help me to find a proper solution. Thank You.

Code:

 If sdr1.Read Then
   If sdr1(1) <> "" Then
     NameLabel.Text = sdr1(0).ToString + " " + sdr1(1).ToString + " " + sdr1(2).ToString
   Else
     NameLabel.Text = sdr1(0).ToString + " " + sdr1(2).ToString
   End If
     dept_id.Text = sdr1(3)
 End If
   sdr1.Close()

In VB & is the string concatenation operator, not +.

Sam Axe
– Sam Axe

2015-04-02 05:08:34 +00:00
Commented Apr 2, 2015 at 5:08 — Sam Axe
– Sam Axe, Commented Apr 2, 2015 at 5:08

Saagar Elias Jacky · Accepted Answer · 2015-04-02 05:08:49Z

3

You need to check whether the data you are comparing is NULL or not before you use it inside any operation:

If sdr1.Read Then
   If Not IsDbNull(sdr1(1)) Then
     If sdr1(1) <> "" Then
       NameLabel.Text = sdr1(0).ToString + " " + sdr1(1).ToString + " " + sdr1(2).ToString
     Else
       NameLabel.Text = sdr1(0).ToString + " " + sdr1(2).ToString
     End If
    End If
    dept_id.Text = sdr1(3)
End If
   sdr1.Close()

or you can simply use

If sdr1.Read Then
   If Not IsDbNull(sdr1(1)) Then
       NameLabel.Text = sdr1(0).ToString + " " + sdr1(1).ToString + " " + sdr1(2).ToString
   Else
       NameLabel.Text = sdr1(0).ToString + " " + sdr1(2).ToString
   End If
   dept_id.Text = sdr1(3)
End If
sdr1.Close()

answered Apr 2, 2015 at 5:08

Saagar Elias Jacky

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Comments

Sam Axe · Accepted Answer · 2015-04-02 05:06:33Z

2

Your column contains a null value. You have to check for nullness before trying to do other comparisons.

So...

If DBNull.Value Is sdr1(1) Then
    '  Got a null value from the database.
End If

If you don't care about whether the value is null, or empty - just want to treat them the same...

If String.IsNullOrEmpty(sdr1(1)) Then
    '  The value is either null or empty.
End If

answered Apr 2, 2015 at 5:06

Sam Axe

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Comments

user4376581 · Accepted Answer · 2015-04-02 05:04:17Z

1

Use If sdr1(1) IsNot "" Then or If Not IsDBNull(sdr1(1)) Then instead for <> that will give you better result

answered Apr 2, 2015 at 5:04

user4376581

Comments

Sai Kalyan Kumar Akshinthala · Accepted Answer · 2015-04-02 05:02:55Z

0

Use String.IsNullorEmpty instead for checking the same

Ex:-

If Not String.IsNullOrEmpty(x) Then
  'Do Something
End If

answered Apr 2, 2015 at 5:02

Sai Kalyan Kumar Akshinthala

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Comments

Martin Prikryl · Accepted Answer · 2015-12-01 08:42:06Z

0

Use instead of If function

try
If sdr1.Read Then
   If Not IsDbNull(sdr1(1)) Then
       NameLabel.Text = sdr1(0).ToString + " " + sdr1(1).ToString + " " + sdr1(2).ToString
   Else
       NameLabel.Text = sdr1(0).ToString + " " + sdr1(2).ToString
   End If
   dept_id.Text = sdr1(3)
End If
Catch ex As Exception

end try

edited Dec 1, 2015 at 8:42

Martin Prikryl

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answered Dec 1, 2015 at 8:22

user5624671

1

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