[Solved] List Box - Display Multiple Columns

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[Solved] List Box - Display Multiple Columns

Postby Steve R. » Tue Nov 16, 2010 4:47 am

In converting my magazine database from MS Access to BASE, an outstanding issue that i encountered was how to combine a last name and a first name in a control and display the combined name while storing the primary key as a BIGINT. After some searching I found this post which proved useful. List box displaying multiple columns

My initial problem was that I had believed that the bound column was based on the underlying table which it wasn't. Turned out that the bound column refers to the "pseudo-column" in your SQL statement. Not only that but it is offset by -1, meaning that "pseudo-column" #3 is really bound column #2. See the attached screen shots. As always, since I am new to BASE, if there is any further advice/clarification, please provide.

Screenshot.png
Data Entry Form, First and Last Name Fields Combined
Screenshot-1.png
Screen shot of the SQL Matrix. Note that the ArtistIDnum is in Column #3 in the SQL Matrix
Attachments
Screenshot-2.png
Note that the Bound Field is identified as Column #2, even though it is Column #3
Last edited by Steve R. on Thu Nov 18, 2010 5:57 pm, edited 2 times in total.
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Re: Combo Box - Display Multiple Columns

Postby Hagar Delest » Tue Nov 16, 2010 9:14 am

Why do you tag your question as solved if you still have a question??? I've removed the tag else, you may not receive many answers. Feel free to add it back afterward.
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Re: Combo Box - Display Multiple Columns

Postby Steve R. » Tue Nov 16, 2010 3:24 pm

It is "solved" from the context that I now know how to display multiple columns. In researching this "how to", I did not find a clear explanation, so I decided to post for the benefit of everyone. Since, I am at the bottom of the learning curve and looking up a steep slope, I may not have a full comprehension of how all this goes to together - so I was also looking for feedback from those who know more.
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Re: List Box - Display Multiple Columns

Postby DACM » Wed Nov 17, 2010 5:10 am

Steve R. wrote:My initial problem was that I had believed that the bound column was based on the underlying table which it wasn't. Turned out that the bound column refers to the "pseudo-column" in your SQL statement. Not only that but it is offset by -1, meaning that "pseudo-column" #3 is really bound column #2. See the attached screen shots. As always, since I am new to BASE, if there is any further advice/clarification, please provide.

Breaking it down, a List Box has a Display field, a Bound (source/primary key) field, and a Data (target/foreign key) field.

The real power behind a List Box in Base is that it allows us to transfer selected (Bound field) data from a source Table/Query to a target Table (Data Field) using a Form. The source Table/Query is known as the 'List source' of the List Box. The target Table is determined by the associated Form. This design can be used in support of "normalized" databases whereby the 'primary key' of the source Table/Query is assigned as the Bound field, which upon user-selection is stored to the Data field of the target Form Table as a 'foreign key'.

Since working with 'key' fields is not user-friendly, the List Box employs a Display field as well. The Display field is used to populate the List Box allowing us to differentiate among source Table/Query records.

Then it just comes down to the designed mechanization of a Base List Box:
  • The List Box Bound field is not available in all cases. The Bound field option requires a multi-column 'Type of list contents' including Table, Query, SQL, or SQL (native).
  • A List Box always uses the first column of the 'List content' as the Display field. Call it what you will (perhaps column "0") but it's really just the Display field.
  • Now if the List Box has a Bound field option, the available Bound fields start with the second column so it becomes option #1 and so on. Obviously, this is confusing because we don't inherently know about the mechanics of the design. As an aside, I think the devs should simply display the available Field/Column names instead of this rather confusing number scheme. But-it-is what-it-is for now.
     Edit: In recent versions of *Office, the Bound field may be set to the Display field -- which in fact is column "0". This allows us to save the Display field to the target table, without creating a redundant, two-column query/SQL as the source List Content. This practice effectively turns a List Box into a Combo Box, but without the free-text feature. Either way, we typically avoid saving the Display field text to the target table, except when working with a flat-file table/database. So a Bound field set to "0" does have it's utility, but this would be a rare practice when working with a properly 'normalized' relational database. 
  • The ability to select a Bound field among multiple columns (even using the lame numbering scheme) becomes important when you use a Table or existing Query as the 'List content' due to the sheer number of columns and their relatively fixed order. So the Display field is always the first column, but the Bound field is any column starting with the second column (column '1') as selected by the Form designer.
  • A dedicated source Query as the 'List content' becomes quite powerful when you consider the power of SQL such as CONCATENATION of multiple fields and ORDER BY clauses, etc. as shown in the example below:

Boundfield.jpg
BoundfieldSQL.jpg

So the devs gave us a cool and flexible design under-the-hood, but then failed to follow-up with something as simple as the column-name in the Bound field spinner. And I find the List Box Wizard to be even more confusing as it seems to use off-the-wall terminology and no graphics for clarity. On the bright-side, the numerical Bound field avoids issues otherwise associated with changing column names.

BTW, your thread title should probably read "Listbox..." because a Base "Combo Box" doesn't have a Bound field function.
Last edited by DACM on Tue Oct 08, 2013 2:46 pm, edited 7 times in total.
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Re: Combo Box - Display Multiple Columns

Postby Steve R. » Thu Nov 18, 2010 6:10 pm

DACM wrote:BTW, your thread title should probably read "Listbox..." because a Base "Combo Box" doesn't have a Bound field function. (emphasis added)
Changed. I ran across this issue last night and finally realized that. In MS Access, both the List Box and Combo Box have the bound field property. I was contemplating an additional post reviewing this distinction, but then I re-read what you wrote again. Thanks for pointing that out. This should be a helpful tidbit for others searching the forum.
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Re: [Solved] List Box - Display Multiple Columns

Postby jenny143 » Mon Nov 14, 2011 3:27 am

good Morning
Nice thread.... :super:

what if i used different tables for this?

example ItemSize from TblItem and UnitName TblUnit???
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Re: [Solved] List Box - Display Multiple Columns

Postby RPG » Mon Nov 14, 2011 3:44 am

Hello

I think it is better to asked your question in a new thread. Give also more information about your problem. This is an already solved thread and only for that reason not a good place to ask a new question.

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Re: [Solved] List Box - Display Multiple Columns

Postby Vedat » Tue Jul 02, 2013 9:17 pm

Sorry for warming this up, but this was exactly what I needed. There is a piece of Information I want to share, which fits IMHO perfectly in this thread.

To access the Data field of the Listbox through OOo Basic, you could simply run following Macro code:

Code: Select all   Expand viewCollapse view
Sub ListboxKundeSelect
   Dim MyForm As Object
   Dim MyBox as Object

   MyForm = ThisComponent.DrawPage.Forms.getByName("MainForm")
   MyBox = MyForm.GetByName ("MyListboxName")
   MsgBox  MyBox.ValueItemList(MyBox.SelectedItems(0)) & " - item from the 2nd column list"   
End Sub
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