PRB: Query to a Report Causes an Inaccurate Sum or Count

- Microsoft Visual FoxPro for Windows, version 3.0 - Microsoft FoxPro for MS-DOS, versions 2.0, 2.5x, 2.6, 2.6a - Microsoft FoxPro for Windows, versions 2.5x, 2.6, 2.6a - Microsoft FoxPro for Macintosh, versions 2.5x, 2.6 - Microsoft FoxPro for UNIX, version 2.6

SYMPTOMS

When you are running a query to a report using two or more databases with a one-to-many relationship and the report is counting or performing other math functions on fields from the parent database, the count or value from the math functions is inaccurate.

RESOLUTION

To get an accurate count, you need to create a user-defined function (UDF). For an example of a UDF that produces the correct count, see "Workaround" in the "More Information" section below.

MORE INFORMATION

When the report performs a count or any math function, it looks to the source database for its information. If the data comes from a query, the source is a temporary table called QUERY. If the query had two or more tables in it with a one-to-many relationship, there will be a matching parent field for each child field.

Steps to Reproduce Problem

1. Use the CUSTOMER.DBF and INVOICES.DBF tables that are found in the <FoxPro_directory>\TUTORIAL subdirectory.

2. Create a report that contains the CUSTOMER.CNO, CUSTOMER.STATE, INVOICES.INO, and INVOICES.ITOTAL fields. Just put the field names in the report and mark the fields coming from CUSTOMER so they don't print repeated values.

3. Group the report by state.

4. In the group footer band, place the CNO field and select Calculate and then Count.

5. Save the report.

6. Open a query and add the CUSTOMER and INVOICES tables.

7. Add the fields listed above to the fields list in the query.

8. Order the query by state.

9. Output the query to the report saved in step 5 above.

Workaround

To obtain the correct count, you can use the following UDF.

   FUNCTION mycount
   PARAMETERS x
   recnum = RECNO()
   mygroup = state
   SELECT DISTINCT customer.cno, customer.state;
     FROM customer, invoices;
     WHERE invoices.cno = customer.cno;
     AND customer.state = mygroup;
     INTO CURSOR counter
   COUNT TO x
   SELECT QUERY
   GO recnum
   RETURN x

REFERENCES

FoxPro for Windows "Getting Started," Chapter 9 FoxPro for Windows and MS-DOS "Language Reference," page L3-1114