Null value in Datareader

[axapta]

Hi Group,
How can I overcome the issue of null values in a datareader. I keep getting
the dbnull error when I try to assign a null value to a text box.

TIA

 

[zacks]

Hi Group,
How can I overcome the issue of null values in a datareader.  I keep getting
the dbnull error when I try to assign a null value to a text box.

TIA

Check out the DataReader IsDBNull Method.

 

[SurturZ]

You need to test each and every field in your dataset if it is Null before
using it.

This annoyed me so much that I now just make all my database fields
non-nullable.

A common solution is to have a "NoNull" function or something that
automatically changes nulls to zero or empty string.

 

[rowe_newsgroups]

Hi Group,
How can I overcome the issue of null values in a datareader. I keep getting
the dbnull error when I try to assign a null value to a text box.

TIA

It's actually quite easy, and requires no checks for DbNull if you
going to a string value:

//////////////
If dataReader.Read() Then
textBox1.Text = dr("MyColumnName").ToString()
End If
/////////////

The ToString() method will happily turn a DbNull into a blank string
("") when called. It's a great time saver

Thanks,

Seth Rowe [MVP]

 

[cfps.Christian]

I always had to do a check on my datareader values as they came out of
the database.

if not dr[0] is DBNull.Value then
textbox1.text = dr[0].ToString() 'I always have option strict on
end if

Kind of a pain, which is why I stopped using null unless I had to.

 

[rowe_newsgroups]

I always had to do a check on my datareader values as they came out of
the database.

if not dr[0] is DBNull.Value then
textbox1.text = dr[0].ToString() 'I always have option strict on
end if

Kind of a pain, which is why I stopped using null unless I had to.

You should be able to just do "textbox1.text = dr[0].ToString()" since
as written above the ToString will convert a dbnull to a blank string.

Thanks,

Seth Rowe [MVP]