BUG: Bad Result If Multiple Aggregate Functions in SQL Stmt

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Article ID: 101553 - View products that this article applies to.
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SYMPTOMS

When an SQL query statement contains multiple aggregate functions, the result set incorrectly contains the same value for all the functions. The result of the first aggregate function is duplicated in the result column of all of the other functions.

CAUSE

Aggregate functions typically do not contain explicit column names for expressions in the SQL query. In SQL queries containing multiple aggregate function calls, the Access database layer does not uniquely identify the return columns for any functions past the first. Therefore, it duplicates the result column of the first function in the result columns of the succeeding functions

This problem did not occur in Visual Basic version 2.0. In Visual Basic version 3.0, the Microsoft Access engine was integrated into the data access functionality. The Microsoft Access engine tracks the column by name, whereas Visual Basic version 2.0 tracks the column by the column offset.

WORKAROUND

Use aliases for the aggregate functions to solve the problem. Replace the SQL statement shown below in the "Steps to Reproduce Problem" section with the following SQL statement, which contains the aliases One and Two for the column names for the separate SUM expressions:
   Select SUM(PubID) as One, SUM(Au_ID) as Two From Titles
				
The Alias names can be anything other than the column name and must be unique within the statement.

After inserting the aliases, run the SQL statement again and notice that the two fields now correctly show the different results.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

Steps to Reproduce Problem

  1. Start Visual Basic.
  2. From the File menu, choose Open Project (ALT, F, O). Open VISDATA.MAK from the VB\SAMPLES\VISDATA directory.
  3. From the Run menu, choose start (ALT, R, S) or press F5 to run the program.
  4. From the Visual Data File menu, choose OpenDatabase. From the sub menu choose MS Access.
  5. From the Open MS Access Database dialog box, select the BIBLIO.MDB file.
  6. For the RecordSet Form Type, select Grid.
  7. Enter the following SQL statement in the SQL Statement window:
       Select SUM(PubID), SUM(Au_ID) From Titles
    						
  8. Click the Execute SQL command Button.
  9. The result shows in a grid window. The two fields have the same value. They should be different.

Properties

Article ID: 101553 - Last Review: October 22, 2013 - Revision: 2.0
APPLIES TO
  • Microsoft Visual Basic 3.0 Professional Edition
  • Microsoft Visual Basic 3.0 Professional Edition
Keywords: 
kbnosurvey kbarchive kbbug KB101553

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