All of my comboboxes are changing when I select and item

Question

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I have 15 comboboxes on my form. They are all linked to the same column in my database.

eg

my database is called: NightshiftDB

Colums: Callsign
Crewname
CrewContact
CrewPhone

I have set up my comboboxes to show the "callsign"

But when I try to select, for example, call sign 650 in the first combobox and say callsign 710 in the next all the comboboxes change to the same callsign.

I am using VB and sql

Any help with this would be fantastic.

Diane

What I have tried:

I have looked at multiple solutions to this problem but am totally confused as they all seem to disagree with each other and nothing I have tried has worked.

VB

Dim copytable_1 As DataTable
        copytable_1 = NightshiftDBDataSet.Tables("callsign").Copy
        ComboBox2.DataSource = copytable_1

I tried the above in the formload event (I thought I could do this for each of the comboboxes) but it threw up the following error

System.NullReferenceException: 'Object reference not set to an instance of an object.'

System.Data.DataTableCollection.this[string].get returned Nothing

I'm not sure what this means, or how to fix it.

Posted 23-Apr-17 13:13pm

Member 13138523

Updated 25-Apr-17 7:16am

Herman<T>.Instance

v3

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Comments

Dave Kreskowiak 23-Apr-17 19:34pm

What does your code look like where you retrieve the data and bind the controls to it?

[no name] 23-Apr-17 19:45pm

I tried finding your code in your "question" so we could see what might possibly the problem but nothing I tried worked.

Richard Deeming 25-Apr-17 15:25pm

The NullReferenceException is quite clear: your NightshiftDBDataSet does not contain a table called "callsign".

Debug your code and examine the NightshiftDBDataSet.Tables collection to see what the table is actually called.

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NightWizzard · Answer 1 · 2017-04-25T07:16:00

If you bind several controls to the same column AND same record, they will all synchronously show the same value because they all are bound to the same source. Think there's a problem in your understanding of databases, records and bound controls - you should read more docu about this.

To keep the controls separated, you have to bind each control to an own dataadapter containing a different record (you may choose different records by adding a WHERE clause each dataadapter's SELECT command to point to a unique value - e.g. the primary key).