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Visual Basic 4 / 5 / 6 Discussion Thread
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Oct 13th, 2008

Null errors in simple database, why?

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If I create a database that has 3 fileds per record; String1, String2 & ResultString. I want the user to enter in the first 2 strings then the program creates ‘ResultString’ by adding the String2 to String 1 itself.
Ie if you enter Big as String1 and Cat as String2 I want ResultString to be BigCat.
I guess I create a sub that is triggered by a change in either 1 of the 2 user entered fields then execute some code as below:

Visual Basic 4 / 5 / 6 Syntax (Toggle Plain Text)
Data1.Recordset.Fileds(“ResultString”) = Data1.Recordset.Fileds(“String1”) + Data1.Recordset.Fileds(“String2”)
Data1.Recordset.Fileds(“ResultString”) = Data1.Recordset.Fileds(“String1”) + Data1.Recordset.Fileds(“String2”)

But I get a Null error. What am I doing wrong?
Many thanks for any help.

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Entropy1024

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Oct 13th, 2008

Re: Null errors in simple database, why?

hi. i think it is much better that you will use the values of the string1 and string2 for the value of Data1.Recordset.Fileds(“ResultString”). You have not yet save any the data so your values for Data1.Recordset.Fileds(“String1”) and Data1.Recordset.Fileds(“String2”) are both null.

Visual Basic 4 / 5 / 6 Syntax (Toggle Plain Text)
Data1.Recordset.Fileds(“ResultString”) = string1 + String2
Data1.Recordset.Fileds(“ResultString”) = string1 + String2

AUGXIS

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Oct 14th, 2008

Re: Null errors in simple database, why?

you need to update the third field by concatinating field1 and field2

debasisdas

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Oct 14th, 2008

Re: Null errors in simple database, why?

Visual Basic 4 / 5 / 6 Syntax (Toggle Plain Text)
Data1.Recordset.Fileds(“ResultString”) = Data1.Recordset.Fileds(“String1”) + Data1.Recordset.Fileds(“String2”)
Data1.Recordset.Fileds(“ResultString”) = Data1.Recordset.Fileds(“String1”) + Data1.Recordset.Fileds(“String2”)

AUGXIS is correct. If youre trying to save the records in the database use the existing data...

Visual Basic 4 / 5 / 6 Syntax (Toggle Plain Text)
With Data1.Recordset
       .Addnew
       .Fields("String1") = "Big"
       .Fields("String2") = "Cat"
       .Fields("ResultString") = "Big" & "Cat"
       .Update
End With
 
or...
 
With Data1.Recordset
       .Addnew
       !String1 = "Big"
       !String2 = "Cat"
       !ResultString = "Big" & "Cat"
       .Update
End With
With Data1.Recordset
       .Addnew
       .Fields("String1") = "Big"
       .Fields("String2") = "Cat"
       .Fields("ResultString") = "Big" & "Cat"
       .Update
End With

or...

With Data1.Recordset
       .Addnew
       !String1 = "Big"
       !String2 = "Cat"
       !ResultString = "Big" & "Cat"
       .Update
End With

Last edited by jireh; Oct 14th, 2008 at 9:14 am.

jireh

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Posting Whiz

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Oct 15th, 2008

Re: Null errors in simple database, why?

Just Try this i think it's works

Data1.Recordset.Fileds(“ResultString”) = Data1.Recordset.Fileds(“String1”) & "" + Data1.Recordset.Fileds(“String2”) & ""

hell_tej

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Oct 16th, 2008

Re: Null errors in simple database, why?

hell_tej it cant be... null value will be returned from

Visual Basic 4 / 5 / 6 Syntax (Toggle Plain Text)
Data1.Recordset.Fileds(“String1”) & "" + Data1.Recordset.Fileds(“String2”) & ""
Data1.Recordset.Fileds(“String1”) & "" + Data1.Recordset.Fileds(“String2”) & ""

because it's a new record and not yet inserted/saved in the database.

jireh

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Oct 16th, 2008

Re: Null errors in simple database, why?

then why not insert the third field also by concatinating the 1st and the 2nd value . still you have to enter 2 values only.

debasisdas

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Oct 25th, 2008

Re: Null errors in simple database, why?

There's another problem you can run into that will give a Null error. If one field is empty there is nothing to concatenate. So how do you check for that? If you read the textbox into a text variable and check for Null, it will never be Null because it is a string type. IsNull only works with variants, I think. So assign the .text from the textbox to a variant and use IsNull. If the .text is not Null, you can use it as-is, or re-assign it to a string variable. If it IsNull, replace it with "" and go on.

rstkw

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