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SQL 2000 uniqueidentifier field and using VB .NET

Posted on 2006-06-14
12
1,012 Views
Last Modified: 2012-06-21
I am trying to learn how to create a unique identifer for an SQL database using VB .NET.

Say this is the table, tblMembers in a database designed to track people.

tblMembers has fields
fldUniqueID as uniqueidentifer
fldFName as varchar
fldLName as varchar

When I try to write to the database I get errors that the type is not compatible with type uniqueidentifier.

I could have used typ Int and simply added 1 each time a new record is created, but I want to learn how to use the uniqueidentifier.

Can anyone explain that to me?

This is just an exercise attempt, here is my user control code off the "Add Member" button...

Public Class ucAddMembers
    Private Sub btnAddMember_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAddMember.Click
        Dim UniqueID As ?????
        Try
            cnnMembers.Open()
            cmdMembers.Connection = cnnMembers
            cmdMembers.CommandText = "INSERT INTO tblMembers VALUES('" & UniqueID & "','" & txtFName.Text & "','" & txtLName.Text & "'" & ");"
            cmdMembers.ExecuteNonQuery()
            MsgBox("Record added successfully!")
        Catch ex As Exception
            MsgBox(ex.Message)
        Finally
            cnnMembers.Close()
        End Try
    End Sub
End Class

0
Comment
Question by:Belificus
12 Comments
 
LVL 3

Expert Comment

by:Titan522
ID: 16906009
uniqueidentifier is unique across the database, it should never be repeated in any table. If you are inserting the value then sql server can't be sure you haven't used the value before. Don't give a value for fldUniqueID. When you do the insert sql server will create its own value and stored in the row.
0
 

Author Comment

by:Belificus
ID: 16906277
Well, I am doing something wrong because SQL did not create a unique ID when the record add attempt was made.

Let me re-create the error messsage and see what it says
0
 

Author Comment

by:Belificus
ID: 16906353
Ok.

When creating the INSERT commandtext, the values are given in the order in which the fields appear.

The error i get if I leave out a variable for the uniqueidentifier is that it cannot convert from type string to type uniqueidentifier.
This is because the INSERT is tyring to put the FNAME text into the first field in the table which is fldUniqueID.

I'd like to learn how to use that table field type, uniqueidentifier.
0
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LVL 44

Expert Comment

by:Arthur_Wood
ID: 16906392
your SQL should read like this:

cmdMembers.CommandText = "INSERT INTO tblMembers (fldFname, fldLName) VALUES('" & txtFName.Text & "','" & txtLName.Text & "'" & ");"

and if the fldUniqueID has been created as Type UniqueIdentifier (which, by the way is the SQL Server equivalent of an Access AUtoNumber field), the fldUniqueID will be automatically created for the record, when it is inserted, so there is no need to provide the value in you insert SQL.

be sure to change (fldFname, fldLName)  to the actual names of those two fields in your table.

AW
0
 

Author Comment

by:Belificus
ID: 16906498
Arthur

I get errors as follows.

Cannot insert the value NULL into column 'fldUniqueID', table 'Members.dbo.tblMembers';coumn does nto allow nulls.  INSERT fails.
The statement has been terminated.

Here is the code:

        Try
            cnnMembers.Open()
            cmdMembers.Connection = cnnMembers


            cmdMembers.CommandText = "INSERT INTO tblMembers (fldFname, fldLName) VALUES('" & txtFName.Text & "','" & txtLName.Text & "'" & ");"


            cmdMembers.ExecuteNonQuery()
            MsgBox("Record added successfully!")
        Catch ex As Exception
            MsgBox(ex.Message)
        Finally
            cnnMembers.Close()
        End Try
0
 
LVL 44

Expert Comment

by:Arthur_Wood
ID: 16910367
ok, then you do it this way:

        Dim UniqueID As GUID =  Guid.NewGuid
        Try
            cnnMembers.Open()
            cmdMembers.Connection = cnnMembers
            cmdMembers.CommandText = "INSERT INTO tblMembers VALUES(" & UniqueID & ",'" & txtFName.Text & "','" & txtLName.Text & "'" & ");"
            cmdMembers.ExecuteNonQuery()
            MsgBox("Record added successfully!")
        Catch ex As Exception
            MsgBox(ex.Message)
        Finally
            cnnMembers.Close()
        End Try

AW
0
 

Author Comment

by:Belificus
ID: 16910905
This will not build.

Will the GUID create a unique value for each new record added?


Error      1      Operator '&' is not defined for types 'String' and 'System.Guid'.      C:\Documents and Settings\binary\My Documents\Visual Studio 2005\Projects\MemberTrakker\MemberTrakker\ucAddMembers.vb      27      38      MemberTrakker
0
 
LVL 44

Assisted Solution

by:Arthur_Wood
Arthur_Wood earned 50 total points
ID: 16911721
ok, this should to it:

 cmdMembers.CommandText = "INSERT INTO tblMembers VALUES(" & UniqueID.ToString() & ",'" & txtFName.Text & "','" & txtLName.Text & "'" & ");"
0
 

Author Comment

by:Belificus
ID: 16911919
Arthur:

It looks like SQL is returning syntax errors that are in memory.  

The msgbox is ERROR [42000][Microsoft][ODBC SQL Server Driver][SQL Server] Line 1: Incorrect Syntax near 'c03fb'.

c03fb looked liek a memory address so I ran it again and got the same line but with 'b56dc' instead.
0
 
LVL 2

Accepted Solution

by:
gstieger earned 250 total points
ID: 16930321
The error is probably as a result of the GUID missing the surrounding single quotes. The differences in error is because a different GUID containing e.g. 'c03fb' or 'b56dc' is getting generated on each run.

;-)

Try changing to:

cmdMembers.CommandText = "INSERT INTO tblMembers VALUES('" & UniqueID.ToString() & "','" & txtFName.Text & "','" & txtLName.Text & "'" & ");"

(single quotes added around GUID)
0
 

Author Comment

by:Belificus
ID: 16935885
Thank you gstieger!

I split points on this because I think Arthur was very close.

gstieger 250
Arthur 50

Thanks again for your help!
0

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