TFILE Correlative

File Translation. The TFILE correlative translates data from one file to another file. It uses data stored in one file to reference the item-IDs of another file in order to retrieve data from the second file. This eliminates the need for duplicating data in related files.

Format

Parameter(s)

Description

The TFILE correlative, placed in the source file, translates data from the destination file. The source file must include an attribute whose data is the same as the item-IDs of the destination file. This attribute in the source file contains the keys—the item-IDs of the destination file—that allow the source file to access any of the data in the destination file.

The TFILE correlative is placed in its own Attribute Definition item in the source file. This Attribute Definition item is created as a synonym for the Attribute Definition item (also in the source file) that defines the attribute mentioned in the preceding paragraph—the one that contains the item-IDs of the destination file. This is done by assigning an S (synonym) code in Attribute 1 and by assigning an attribute number which is the same as the attribute number of the attribute containing the destination file’s item-IDs. The TFILE correlative itself specifies:

1. The name of the destination file

2. The attribute number of the attribute in the destination file from which data is to be translated

3. What action is to be taken if there is no data value in that attribute.

Using the TFILE Correlative

Assume you have a BOOK-CATALOG file that contains a book store’s inventory. The file dictionary includes Attribute Definition items for author, title, and price, among others. The item-IDs in BOOK-CATALOG are unique code numbers that identify each book. Here is some sample output from the BOOK-CATALOG file:

Assume in addition that you have another file called ORDERS. The file dictionary includes Attribute Definition items for quantity ordered (QTY), and unique book codes for each book (BOOKCODE).

Here is a report showing some sample data in the ORDERS file:

Using TFILE correlatives, you can link the data contained in the BOOK-CATALOG file to the data contained in the ORDERS file, thus avoiding unnecessary duplication of data. The ORDERS file requires only one set of data to access the BOOK-CATALOG file, namely the unique book code numbers which are the item-IDs of BOOK-CATALOG. These numbers are stored as Attribute 1, BOOKCODE, in the ORDERS file.

The following three Attribute Definition items in the dictionary of the ORDERS file contain the TFILE correlatives that are necessary to translate data from the BOOK-CATALOG file to the ORDERS file:

The preceding synonym for Attribute 1, BOOKCODE, uses the TFILE correlative to access Attribute 2, TITLE, in the BOOK-CATALOG file.

The preceding synonym for Attribute 1, BOOKCODE, uses the TFILE correlative to access Attribute 3, PRICE, in the BOOK-CATALOG file. Since this is a numeric value, it is right-justified. A masked decimal conversion is applied to the output.

The preceding Attribute Definition contains an F correlative that includes an embedded TFILE correlative. The TFILE correlative obtains the unit price from Attribute 3, PRICE, of BOOK-CATALOG. The F correlative then multiplies the unit price by the data in Attribute 2, QTY, of ORDERS to arrive at the total amount for each line item.

With these three Attribute Definition items in place, it is now possible to replace the data in the attribute BOOKCODE with the titles and prices that are stored in the BOOK-CATALOG file.

Compare the following orders report with the preceding one:

See Also

Correlatives and Conversions Reference