Use SQL to Easily Update Multi-Key Files
July 27, 2005 Hey, Ted
Updating a single record in a file that has a lot of key fields often requires SQL commands with complicated WHERE clauses. I use a technique with web applications that greatly simplifies the WHERE clause. I have never seen this technique published before, so I hope you can use it.
When I retrieve a record that will be updated through a Web browser, I select the relative record number along with the data.
SELECT RRN(MyFile) as storedRRN, MyFile.* FROM MyFile WHERE ENBBTYPE = 'COPY' and ENBBTCH# = 4062
When I update, I need only refer to the relative record number.
UPDATE MyFile SET SomeCode = 'FRO', Description = 'Front' WHERE RRN(MyFile) = storedRRN
–Chuck Wakelee, Cardone Industries
Since I favor making things as simple as possible, I am glad to publish Chuck’s tip. It may not be worth my mentioning it, but Chuck’s SQL statements are bare-bones illustrations. To use this technique in a program will require the use of host variables.