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How do I write a "variable as variant" array to a microsoft access mdb file?

Posted on 2006-07-20
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Last Modified: 2010-04-30
So far im able to write string variables into a microsoft mdb file.
My question is, what do i need to change in my code to write a variant array into an mdb?

Dim conn As New ADODB.Connection
    Dim rs As ADODB.Recordset
    Set rs = New ADODB.Recordset
    conn.Open "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=c:\test\MyDataBase.mdb;"
    rs.Open "MyTable", conn, adOpenDynamic, adLockOptimistic
    rs.AddNew
    rs.Fields("Test1").Value = StrDocName        'I write a string variable here into Field column  "Test1" as a new value
    rs.Fields("Test2").Value = StrStreamPath     'I write a string variable here into Field column "Test2" one as a new value
    '    rs.Fields("Test3").Value = VariantArray        'Now I want to write a variant array into the field, how can i do this?
    rs.Update
    rs.Close
    Set rs = Nothing
   
    conn.Close
   
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Question by:sbronsge
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Accepted Solution

by:
maonas earned 400 total points
ID: 17145750
You cannot define a field in MS Access with array data type.You can define only Text, Number, Memo, Number, Date/Time...data type for an associated field.
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Expert Comment

by:Patrick Matthews
ID: 17145765
Hi sbronsge,

>     '    rs.Fields("Test3").Value = VariantArray        'Now I want to write a
> variant array into the field, how can i do this?

You cannot write an array to a field--a field contains a single data element, while arrays are n-dimensional structures
with potentially many members.  You can write a particular member to a field, though:

rs.Fields("Test3").Value = VariantArray(5) 'writes the member with index 5

Regards,

Patrick
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Expert Comment

by:alainbryden
ID: 17145788
mdb Recordsets store string objects or doubles. If I'm malinformed in saying this, stop me now, otherwise continue. They do not store objects or references, and storing a reference as a string in one will not keep the array valid, and it will still be garbage collected when your program ends.

Your term "VariantArray" does not point to all those variants that you are wishing to store. What it points to is the memory location of first Variant in that array, which in turn points to the next, and so on. Storing this variable would do nothing but store a reference to the memory location of the first variant (which, as I said, would dissapear after garbage collecting)

The only way to do this would be to create a variable number of fields and store string representations of the contents of the array. The more complicated the variants in the array, the more fields you'll need to store each one. That's all you can do. I'll give you a start by saying you'll probably need something like this:

    rs.Fields("Test1").Value = StrDocName
    rs.Fields("Test2").Value = StrStreamPath
    For Cnt = 1 to UBound(VariantArray)
           rs.Fields("Test" & (2 + Cnt) ).Value = Str( VariantArray(Cnt) )
    Next Cnt
    rs.Update
    rs.Close


Let me know if there's any further guidance I can give you.

Alain
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Author Comment

by:sbronsge
ID: 17146719
thx for the updates.

So far I tried all suggestions, but best way is to implement a counter like Alain told.
But I have a problem with this code.
Its about:


    For Cnt = 1 to UBound(VariantArray)
           rs.Fields("Test" & (2 + Cnt) ).Value = Str( VariantArray(Cnt) )
    Next Cnt


Str( VariantArray(Cnt) )    > in my Watch window I see the correct value for my variant array: " 12121212".
but when I select "Value" and see the watch window, I got an error: Item cannot be found in the collection corresponding.....
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Expert Comment

by:alainbryden
ID: 17146762
The Watch window will not be able to view the value being after it's placed in the database because viewing a value requires a method call to the database with the proper key, and the watch does not do method calls, it merely surveys memory locations. My bet is if you end your program and open up the database is MS Access, it will all be there.

Alain
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Author Comment

by:sbronsge
ID: 17153336
it works thanks Alain and Matthewspatrick!
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Author Comment

by:sbronsge
ID: 17153344
guys how do I give alain and patrick points for their answers. I want to give them points?
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Expert Comment

by:alainbryden
ID: 17161414
Post in the Community Support area, and tell them that you accidentally gave points to the wrong person, they'll fix it for you.

http://www.experts-exchange.com/Community_Support/
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Expert Comment

by:Patrick Matthews
ID: 17161518
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