How to Perform REPLACE for Two Databases w/ Common Field (116037)


The information in this article applies to:

  • Microsoft Visual FoxPro for Windows 3.0
  • Microsoft FoxPro for Macintosh 2.6a
This article was previously published under Q116037

SUMMARY

To update more than one record in a database from another, similar database, you may need to check for an end-of-file (EOF) marker during each iteration of the REPLACE operation. This is best accomplished with a DO ... WHILE loop, as demonstrated below.

NOTE: In order for this process to work, the two databases must have a common key field.

MORE INFORMATION

To demonstrate this process, we'll use the CUSTOMER database in the FoxPro TUTORIAL subdirectory. First, we'll copy CUSTOMER to a new database called NEWCUST, then we'll delete the contents of the COMPANY field, and then we'll restore the contents of the COMPANY field using the COMPANY field information in CUSTOMER.
  1. Set the default directory to the location of CUSTOMER.DBF. For example, in FoxPro 2.x, issue the following command in the Command window: 
          SET DEFAULT TO C:\<FoxPro_directory>\TUTORIAL.
    In Visual FoxPro, Issue the following: 
          SET DEFAULT TO C:\<FoxPro_directory>\SAMPLES\DATA
    NOTE: In Visual FoxPro, you will also need to change all references below from from CNO to CUST_ID.
  2. In the Command window, issue the following commands: 
          USE customer
      COPY TO newcust
      SELECT 0
      USE newcust
      ** the following command has no spaces between the quotation marks
      REPLACE ALL company WITH ""
      ** BROWSE the table with the empty COMPANY field contents
      BROWSE
      CLEAR ALL
      CLOSE ALL
      ** open a new program file called TEST
      ** if a program called TEST already exists, choose another name
      MODIFY COMMAND test
  3. In the edit window for the TEST program, type the following commands: 
          SELECT 0
      USE customer
      SELECT 0
      USE newcust

      SELECT customer

      ** while not at end of file of CUSTOMER, do some actions
      DO WHILE !EOF()
         ** select the destination table
         SELECT newcust
         ** replace the empty COMPANY field with data from CUSTOMER where
         **   the common key field is the same
         REPLACE newcust.company WITH customer.company;
            FOR newcust.cno = customer.cno
         ** select the source table again to go to next record
         SELECT customer
         SKIP
      ENDDO
      SELECT newcust
      ** BROWSE the table with the newly filled COMPANY data
      BROWSE
    NOTE: If the first database (that is, CUSTOMER) is indexed on the common key field between the two tables, replace the commands in step 3 with the following: 
          SELECT 0
      USE customer ORDER TAG cno
      SELECT 0
      USE newcust
      REPLACE ALL newcust.company WITH customer.company FOR ;
         seek(cno,"customer")
  4. Save TEST.PRG and then run it.

REFERENCES

"Language Reference," (Windows and MS-DOS) pages L3-312, L3-470, L3-480, L3- 816, L3-861, L3-1040, L3-1108

"Language Reference," (Macintosh) pages 271, 396, 404, 651, 685, 827, 884
Modification Type:MajorLast Reviewed:10/15/2003
Keywords:kbcode KB116037 kbAudDeveloper
©2003 Microsoft Corporation. All rights reserved.