title: How to add functionality for ComboBox <Select All> in Microsoft Access forms
body: <p>So I posted a question the other day about an access form that needed to have a "Select All" option added to the 2 ComoBoxes. I was able to add in the option to the 2 of them using a union. However, the options do nothing as of yet. I found the Query that takes the form parameters from the ComboBox and this is where I need to add in the option to select all, except after staring at it for hours I've got no clue again.</p>
  
  <p>The Database wasn't written by me, it's approximately 10 years old and was was given to me to add some new features. I have done that, and the owner complained that the "Select All" buttons have never worked. After research, the buttons have VB script that clears the ComboBox input to nullified value. I am planning on scrapping those now since I have added the option to the ComboBox itself. </p>
  
  <p>The SQL query that reads combo input looks like this:</p>
  
  <pre><code>PARAMETERS [Forms]![ReportCentre]![cboTreatmentType] Short, [Forms]![ReportCentre]!      [cboTreatmentDate] Short;
  
  
  SELECT addresses.*,
         [firstname] &amp; "" &amp; [lastname]
         AS Name,
         [street] &amp; "," &amp; [suburb] &amp; "" &amp; [stateorprovince] &amp; "" &amp; [postalcode]
         AS
         Address
  FROM   addresses
  WHERE  ( ( ( addresses.treatmentid ) = [forms] ! [reportcentre] !
                                                  [cbotreatmenttype].[Value] )
           AND ( ( addresses.treatmentdate ) = [forms] ! [reportcentre] !
                                                   [cbotreatmentdate].[Value] )
           AND ( ( addresses.birthmonth ) LIKE [forms] ! [reportcentre] !
                                               [txtbirthmonth].[Value]
                                                   &amp; "*" ) )
          OR ( ( ( addresses.treatmentid ) IS NULL )
               AND
         ( ( addresses.treatmentdate ) = [forms] ! [reportcentre] !
                                             [cbotreatmentdate].[Value] )
               AND ( ( addresses.birthmonth ) LIKE [forms] ! [reportcentre] !
                                                   [txtbirthmonth].[Value]
                                                       &amp; "*" ) )
          OR ( ( ( addresses.treatmentid ) = [forms] ! [reportcentre] !
                                                   [cbotreatmenttype].[Value] )
               AND ( ( addresses.treatmentdate ) IS NULL )
               AND ( ( addresses.birthmonth ) LIKE [forms] ! [reportcentre] !
                                                   [txtbirthmonth].[Value]
                                                       &amp; "*" ) )
          OR ( ( ( addresses.treatmentid ) IS NULL )
               AND ( ( addresses.treatmentdate ) IS NULL )
               AND ( ( addresses.birthmonth ) LIKE [forms] ! [reportcentre] !
                                                   [txtbirthmonth].[Value]
                                                       &amp; "*" ) )
          OR ( ( ( addresses.treatmentid ) IS NULL )
               AND
         ( ( addresses.treatmentdate ) = [forms] ! [reportcentre] !
                                             [cbotreatmentdate].[Value] )
               AND ( ( addresses.birthmonth ) IS NULL ) )
          OR ( ( ( addresses.treatmentid ) = [forms] ! [reportcentre] !
                                                   [cbotreatmenttype].[Value] )
               AND ( ( addresses.treatmentdate ) IS NULL )
               AND ( ( addresses.birthmonth ) IS NULL ) )
          OR ( ( ( addresses.treatmentid ) = [forms] ! [reportcentre] !
                                                   [cbotreatmenttype].[Value] )
               AND
         ( ( addresses.treatmentdate ) = [forms] ! [reportcentre] !
                                             [cbotreatmentdate].[Value] )
               AND ( ( addresses.birthmonth ) IS NULL ) ); 
  </code></pre>
  
  <p>I know it's messy and hard to understand, which is why im asking for help. How do I get that to validate a "Select All" option for both ComboBoxes?</p>