View source for The most frequently asked questions and their answers

Common questions and answers for those migrating from [[Microsoft Access]] (MSA) to OpenOffice [[Base]].

This is a user community effort - add to the knowledge base if you can.

Please however try to keep the questions and answers general. If there is an answer regarding a feature specific version of MSA then include the version number also.

'''Specifically, please only update the wiki if you have an answer for the question you are adding.''' ( ''If you may need to get back shortly with the answer don't let that stop you from getting the question in first however - just come back before long'' ) 

For asking '''specific questions''' or for general help it would be appropriate to then ask on either the:
[https://forum.openoffice.org/en/forum/viewforum.php?f=13 Base Forum] or on  
[https://openoffice.apache.org/mailing-lists.html#users-mailing-list-public the Base users mailing list].

== Can I use Microsoft Access databases (.mdb) in Base? ==

On Windows: yes. You cannot open them directly via <code>File|Open</code>, but you can access the data therein. For this, you need an Open Document Base file (*.odb), which holds the connection information. For details see [[Connecting to Microsoft Access]].

You can modify the data in the tables and you can add and remove records.
You can create new tables, but you cannot alter the structure of existing tables.

Queries in MS Access are shown as views in the table container. You can use the query results, but you have no access to the underlying definitions and you cannot alter them.

You cannot read MS Access forms or reports.

== Can I read my Base database from MS Access? ==
There is no way to use the table linking mechanism in Access to connect to a Base database.

It is possible for a Base database to update data in the Access database. At this time this will require however that the Access database be opened and locked by the Base file.

Data could also be passed back to the Access database by creating a linked CSV file in the Base database. Then linking to this CSV file to a table in the Access database.

== Can I create an Access database (mdb file) with Base? ==

No. Base can not create a new Access database file; or new tables, queries, forms etc. within an existing mdb file.

== Can I create a Switchboard in Base? ==

Base does not currently have a switchboard style form wizard. It is possible to achieve a very similar effect however using either of two techniques.

* Opening a default form via a macro

* Using a stand alone form to launch the Base database

== Our Access databases uses "Workgroup Security" to control group/user permission to view/maintain data? ==

This question points out what is a fundamental difference between OOoBase and MS Access (MSA). In the case of MSA there is one and only one database engine in use - although you may link tables in MSA to external datasource - MS Jet is still the only database engine actually used by MSA.

In Base (OOoBase) this is not the case at all. The Base database document is simply a front end (client application) to a variety of database engines. In one of these forms it embeds a HSQLDB database into the ODB file itself, many people simply see this as the only Base database format. That is totally mistaken. In this instance of an embedded database there is no support for multiple users and of course no support for groups therefore. However, that is only one of the ways Base can be configured.

You are free to use Base as the front end to a HSQLDB database in server mode. HSQLDB is a very small footprint, low administration database engine and in server mode has full support for users / groups. For larger numbers of users you could just as easily configure Base to work with MySQL, PostgreSQL, Firebird, Oracle, or MS SQL Server.

There is another significant difference between MSA and Base regarding this then. In MSA you would deploy one MDB (or one of its variants ) file, then have each user in the workgroup see this file and open it.

In Base each user would have their own ODB file and each of these would be connected to the shared data server. In this way each user would have their own space for custom queries and reports - but it makes distribution of common forms, queries and reports more work.

== Is a Form in Base different from a Form in MSA? ==

Yes.  There are very real differences between how Forms are implemented in Access and Base.

=== Virtual forms within Base forms ===

Virtual forms in Base are called "subforms". You can manage them opening the form in Edit mode and then clicking on "Form Navigator", in "Form Design" toolbar.

== Where are the Delete / Update queries? ==
Base does not currently support building delete / insert / update queries in the designer.

=== Equivalent actions === 
==== ''using the Query Designer'' ====
You can achieve the equivalent actions in the GUI using the designer and or SQL commands.

==== ''using a macro'' ====

== I want to filter my form based on the contents of a combobox? ==

== Converting my [[VBA]] modules to Base modules ==

=== What happened to me? ===

There is no exact duplicate to the ME pseudo variable in VBA. 

In Access VBA 'me' has attributes of two separate objects in OOoBasic: 
TextDocument and DataForm

The TextDocument object would be used for controlling the window size and placement on the screen for instance. 

The DataForm meanwhile supports result set functions, such as First, Filter, InsertRow.

In AOO Basic the pseudo variable thisComponent normally would be the TextDocument, while thisComponent.DrawPage.Forms(0) meanwhile would reference the first DataForm owned by the TextDocument.

Perhaps a still closer equivalent is to use the object ownership hierarchy to get to the form. For example, if we had a single table form with a button, then in the macro called by the 'onClick' (or as AOO Base calls it the 'When initializing' event) we would do this: Create a macro in a library named onButtonClick( oEv as object )
<syntaxhighlight lang="oobas">
    sub onButtonClick( oEv as object )
      ' oEv is the event object passed automatically
      ' it has a property SOURCE which is the 
      ' button that initiated this call
    
      dim oForm as variant
    
      oForm = oEv.Source.Model.Parent
       ' oForm is now the virtual form objct
      
      dim oDocument as variant
      
      oDocument = thisComponent
       ' oDocument is now the textDocument displayed in
       ' the window on screen
    
    end sub
</syntaxhighlight>

=== Where is findfirst? ===

Base does not appear to have a FindFirst function on the rowset like MS Access, what is the equivalent Base function?

MSAccess VBA example:

Say there is a VB combo box which lists all the prospects in the database and allows the user to select a particular prospect and then have the form automatically go to that person's data record.
<syntaxhighlight lang="vb">
  Private Sub Find_Combo_AfterUpdate()
  Dim strCriteria As String
  
  strCriteria = "[Prospect_ID] =" & Me.Find_Combo
  
  Me.recordsetclone.FindFirst (strCriteria)
  If me.recordsetclone.NoMatch Then
      MsgBox "No entry found"
  Else
      Form_F_Prospects.Bookmark = me.recordsetclone.Bookmark
  End If
  
  End Sub
</syntaxhighlight>

For this type of simple single column search it is easy enough to create our own find first equivalent with OOoBasic:
<syntaxhighlight lang="oobas">
 Sub Find_Combo_AfterUpdate( OEv as Object)
    ' Oev is the event object automatically sent
    ' to sub procedure call
    ' Oev will have a property Source
    ' that is the control that triggered
    ' the call to this procedure
  
  Dim oForm as variant ' The dataform obejct 
  
  Dim oComboBox as variant ' The combobox control
  
  Dim oBkMark as variant
  
  oForm = oEv.Source.Model.Parent
  
  oComboBox = oForm.getByName( "Find_Combo" )
    
  oBkMark = FindFirst( oForm.CreateResultSet(), "Prospect_ID", oComboBox.Text )
      ' oForm.CreateResultSet() is equivilant here to me.recordsetclone
  if not IsEmpty( oBkMark ) then
  		oForm.moveToBookmark( oBkMark )
  else
  	msgBox( oComboBox.Text & " not found" )
  end if
  
 end sub

 function FindFirst( oRS as variant, ColName as string, SearchVal as string ) as variant
        ' oRS is a resultSet object
        ' ColName is the name of a column in the resultset
        ' SearchVal is
    dim colIDX as integer
    dim NotFound as variant
  
    FindFirst = notFound
    colIDX = oRS.FindColumn( ColName )
    oRS.First
    do 
      if oRS.getString( colIDX ) <> Searchval
        oRS.Next
        if oRS.isAfterLast then
          exit do
        endif
      else
        FindFirst = oRS.getBookMark
        exit do
      end if
    loop while oRS.isAfterLast <> True
  
 end function
</syntaxhighlight>

=== How do I set the filter for a sub-form only? ===

=== Is there an equivalent to DoCmd RunSQL ===

Yes, in AOO Base you would use either a Statement or PreparedStatement object to achieve the same function. With AOO Base you must also decide between using execute and executeUpdate.

For example if you had the VBA line
<syntaxhighlight lang="vb">
  DoCmd RunSQL( "SELECT * FROM tContacts" )
</syntaxhighlight>

it would become in AOO Base
<syntaxhighlight lang="oobas">
  Dim oStatement as variant
  
  oStatement = OForm.ActiveConnection.CreateStatement
    ' Where oForm is a DataForm object
    ' NOTE you could do exactly the same thing with
    ' a resultSet or rowSet object also
    ' oStatement = OResultSet.ActiveConnection.CreateStatement
  
  oStatement.execute( "SELECT * FROM ""tContacts"""  )
  
If on the other hand the VBA line where
  DoCmd RunSQL( "DELETE FROM tContacts WHERE Status = 'INACTIVE'" )

then we would use the executeUpdate method on a statement

  oStatement.executeUpdate( "DELETE FROM ""tContacts"" WHERE ""Status"" = 'INACTIVE'"  )
</syntaxhighlight>
The rule is - 
*if your SQL statement will return records you use execute or executeQuery.
*if the SQL statement returns no records then you must use executeUpdate.

== If I use Lookup fields/columns in my  Access tables what can I do in Base? ==
There are two parts to this answer, given that Base does not support Lookup column types in tables.

When a table is displayed in a custom form use of a bound listbox will give you the same functionality. An example of [[adding a listbox to a form]] and to a grid control on a form is at this page.

In a table view ( double clicking on the table name ) there is no equivalent to this.

==How do I use Domain Aggregate functions in Base?==

Domain Aggregate functions such as '''DCount''', '''DLookup''', '''DMax''' etc have no direct equivalent in Base. You will have to write or design queries to return these results using the appropriate SQL functions.

==How do I add Calculated Controls to my forms and reports?==

Controls in Base forms and reports cannot be used to perform calculations. There are two methods available to get a calculated result on a form or report.

===Using a query===
Modify the underlying data source of the form or report to perform the calculation for each record and return the result as a (calculated) field.

===Using a macro===
If you need your control to update as data is entered into a form, you will need to write a small macro to perform the calculation and assign it to an appropriate event on one of the data entry controls (e.g. the Text modified event).

[[Category:Database]]
[[Category:Base Documentation]]
[[Category:User FAQ]]
[[Category:Documentation/FAQ]]
[[Category:Documentation/FAQ/Databases/MS Access]]