Senin, 31 Juli 2017

Re: [MS_AccessPros] IIF as Query Criteria

 

All of the sudden my form is working again and I can try some things.  I see immediately that the "result if false" needs to be Like "*".



---In MS_Access_Professionals@yahoogroups.com, <david.pratt@...> wrote :

OK, I am trying to follow.  Here is what I think I am doing.  So three parts: (1) criteria, (2) result if true, (3) result if false; all three parts separated by commas.  And the IIF statement is located in the query Criteria row for the field named COMPARATOR.

STATEMENT: IIF(Me.chkLessThan, <> "<", "") 
      located in the query criteria row under the field named COMPARATOR

Part 1, the Criteria:
         IIf chkLessThan (meaning if chkLessThan is = true)

Part 2, Result if True:  <> "<"
  means set the criteria for the COMPARATOR field such that the query only shows the rows of data where the string character in the COMPARATOR field is not the 'less than' symbol.  Perhaps I should enclose in quotes differently?  Maybe "<> '<' " ?

Part 3, Result if False: ""
 means if chkLessThan is false, then the criteria for the COMPARATOR field should be set to "" (blank) so that no filtering occurs.  Perhaps this should be a wild card instead like "*"?

Until I can get the form to quit closing on me, I can't try any of these.

Thank you for the response,


---In MS_Access_Professionals@yahoogroups.com, <davewillgmale@...> wrote :


I am not an expert, but your Iif query seems wrong. An Iif query has three parts separated by commas: Criteria, result if True, result if False. In your query, the first part could be True or False as it's a checkbox, but the second part is not a result - you've put <>"<", not just "<". Your third part is OK and gives a blank if the checkbox is False.
 
----- Original Message -----
Sent: Monday, July 31, 2017 3:16 PM
Subject: [MS_AccessPros] IIF as Query Criteria

 

I have an unbound form whose purpose is to show the analytical results from various water samples. The form contains two list boxes.  The first list box contains the list of samples and the second list box shows the results of the selected sample. I also have two combo boxes which are used to filter the list of samples. 

All of this works well. However, I am trying now to be able to also filter the sample results such that if any of the sample results are "less than" the detection limit, the result is not included in the list of sample results.  I have a field named COMPARATOR in the tblSampleResults and that field is in the query used by the list box.  

I added a checkbox to the form as chkLessThan and want to use the value in that checkbox to determine if any "less than" results show up in the list box.  So far I cannot get this to work.  I can "hard code" the query criteria by placing <> "<" in the criteria for COMPARATOR and that works fine.  But I cannot get the syntax correct for an IIF statement in the criteria.

Basically I need the query criteria for the COMPARATOR field to be:
       IIf([me].[chkLessThan],<>"<","")
When I put this in the query criteria Access changes it to
     IIf([me].[chkLessThan],([tblSampleResults].[Comparator])<>"<","")

When I go to form view, Access thinks this is a Parameter query and asks me what the value is for Me.chkLessThan.

Can you help me with the correct syntax or is perhaps IIF not allowed in the criteria of a SQL statement?

The SQL which is generated by the query design is:
SELECT [ParameterName] & ", " & [Units] AS [Parameters], [Result]) AS Results, tblSampleResults.Comparator
FROM lu_tblAnalyses
INNER JOIN ((tblSampleResults INNER JOIN tblParameters ON tblSampleResults.ParameterID = tblParameters.ParameterID) INNER JOIN lu_tblParameterGroups ON tblParameters.ParameterGroupID = lu_tblParameterGroups.ParameterGroupID) ON lu_tblAnalyses.AnalysisID = tblParameters.AnalysisID

WHERE (((tblSampleResults.Comparator)=IIf([me].[chkLessThan],(tblSampleResults.Comparator)<>"<","")) AND ((tblSampleResults.SampleID)=[Forms]![frmSelectSample]![lstSamples]))
ORDER BY lu_tblParameterGroups.ParameterGroupSort, tblParameters.ParameterSort;


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Posted by: david.pratt@outlook.com
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