Tfile Code - Translation

The Tfile code provides a method for translating a value from a source file into a value taken from another file (the translation file). The value in the source file is used as an item-id in a translation file. This eliminates the need to duplicate data.

Input/Output Conversion

Output conversion is valid. The Tfile code has a parameter (outputAttr) that specifies the attribute in the translation item to use for output conversion.

Input conversion is valid. The Tfile code has a parameter (inputAttr) that specifies the attribute in the translation item to use for input conversion.

Syntax

T{{[DICT || *]}fileSpec};transCode{[valueNo||:delimiter]};{inputAttr};{outputAttr}{;breakAttr}

Syntax Elements

'[708] text CANNOT BE CONVERTED'

Comments

Attribute

The Tfile code can be used in attribute 7 or 8 of the data definition item.

If translating a multivalued attribute, or if comparisons and sorts are required, the Tfile code should be used in attribute 8 of the data definition item.

If selection criteria may be used, you can use attribute 8 for the Tfile code or you can use attribute 7 and set up special items in the translation file to carry out the input translation required.

File Specifier

If a file specifier is included, the Tfile code uses the data value as the item-id for the specified translation file. It then returns the requested attribute value from that item.

If the file specifier is omitted, the data value must contain both a file specifier and an item-id. One way of generating the file specifier is to use the NF, NFA, NFD, NFF, NFN and NFS operators in an A or F code conversion. Dynamically generating the file specifier can:

• Simplify and generalise the translation definition when the source file is also the translation file. This allows the definition to used with multiple data sections and allows for the renaming of the file.
• Reduce the generation and administration of very large and complex dictionaries.
• Simplify and generalise the translation by allowing the translation file name to be generated from a source file value.
• Enhance the efficiency of some queries that use the Tfile conversion code.

Note that when the Tfile code is used in conjunction with other conversion codes, the syntactical conventions of the other code must be followed. For example, if the Tfile code is used with an F code conversion, the Tfile code specifications must be enclosed in parentheses.

Special Items

The special items in the translation file have as item-ids values that the attribute subject to translation may be compared with in an English sentence. Attribute inputAttr within these items contains the translate value that will be compared to values on file. Typically, values in an English sentence are output values, so that the special input translation items are effectively the inverse of the output translation items.

Tfile Code Examples

The first two examples show how the Tfile code is used to translate attribute values contained in the GUESTS file for use by the ROOMS file and vice versa.

Example 1

GUESTS file items contain the last name of the guest in attribute 2. The ROOMS file does not list guests. In the dictionary of the ROOMs file the following data definition item is set up:

     GUEST-NAME

001  A

002  0

003  Current Guest

004

005

006

007

008  TGUESTS;X;;2

009  T

010  15

This definition tells the system to take the value of attribute 0 in the ROOMS file item (the item-id) and use it as the item-id of an item in the GUESTS file (the translation file). If the item exists then use its attribute 2 as GUEST-NAME, otherwise use null.

Notice that attribute 2 of the data definition item references item-ids. This is useful in two respects:

• It allows translation of item-ids in any other file.
• It does not require the inclusion of an attribute in the translation file that specifically associates item-ids in another file. An example of an attribute containing a 'reference' value in the translation file is provided in Example 3.

Use of the data definition item GUEST-NAME is shown by the following:

:LIST ROOMS WITH GUEST-NAME "Hen]" HDR-SUPP

ROOMS Current Guest..
143   Hennessey

Example 2

Similarly, the GUESTS file contains no information about the room occupied by a guest. That information is translated from the ROOMS file by setting up a number of data definition items in the dictionary of the GUESTS file including the following:

ROOMS file items contain the room-code in attribute 1.

     ROOM-CODE

001  A

002  0

003  Room]Code

004

005

006

007

008  TROOMS;X;;1

009  L

010  4

This definition tells the system to take the value of attribute 0 in the GUESTS file item (the item-id) and use it as the item-id of an item in the ROOMS file (the translation file). If the item exists then use its attribute 1 as ROOM-CODE, otherwise use null.

The following shows the use of ROOM-CODE:

:LIST GUESTS WITH ROOM-CODE = "P" ROOM-CODE NAME HDR-SUPP

GUESTS Room  Guest Name.........
       Code
535    P     Linda P. Evans

Example 3

Assume an inventory/order type data base with a VENDOR file that only contains names and addresses and an ORDERS file that contains source information about the orders.

Each item in the ORDERS file contains:

001  Part Number

002  Quantity

003  Price

004  Date ordered

005  Date received

006  Vendor code (reference value)

Each item in the VENDOR file contains:

001  Vendor name

002  Street address

003  City

004  ZIP code

The appropriate data definition items are set up to convert the dates and prices to a desired format. To combine information about the vendor and the product ordered, the following data definition items are set up in the dictionary of the ORDERS file:

     VENDOR

001  A

002  6

003  Vendor

004

005

006

007  TVENDOR;C;;1

008

009  L

010  12

     V.ADDR

001  A

002  6

003  Address

004

005

006

007

008  F;6(TVENDOR;C;;4);C, ;:;6(TVENDOR;C;;3);:;C, ;:;6(TVENDOR;C;;2);:

009  L

010  35

Note that the Tfile code in V.ADDR is combined with the F code. Although this can be considered as an example of multiple codes, the syntax of the F code governs the syntax for the whole specification. In the context of the F code syntax, the Tfile codes are conversion codes and are preceded by an attribute number.

The F-code functions in reverse Polish format. Therefore, the value that is to be output first is specified last as shown in the following:

F;6(TVENDOR;C;;4);C, ;:;6(TVENDOR;C;;3);:;C, ;:;6(TVENDOR;C;;2);:

where:

F indicates invoke the F-code processor.

6(TVENDOR;C;;4) means take the value of attribute 6 in the ORDERS file item and retrieve from the VENDOR file the item with this item-id. Then extract outputAttr (attribute 4: ZIP code) of this item and push it onto the stack.

C,spacemeans push the literal ', ' onto the stack.

: means concatenate the top stack entry onto the front of the next stack entry to replace the top stack entry.

6(TVENDOR;C;;3) means take the value of attribute 6 in the ORDERS file and retrieve the item in VENDOR with this item-id; then extract the outputAttr (attribute 3: City) of this item and push it onto the stack.

: means concatenate the top two stack entries.

C,spacemeans push the literal ', ' onto the stack.

: means concatenate the top two stack entries.

6(TVENDOR;C;;2) means take the value of ORDERS file attribute 6, retrieve this item from VENDOR, extract outputAttr (attribute 2: Street address) and push it onto the stack.

: means concatenate the top two stack entries.

You can now use the following English sentence to get a report similar to the one shown below:

:LIST ORDERS VENDOR V.ADDR HDR.SUPP

ORDERS  Vendor......   Address............................

8801    Schlussel AG   40 Potsdamer St., Berlin 30, D2000

8802    Key Products   35 High St., Maida Vale, NW4 4BT

8803    CEP            100 Main St., Irvine, CA92714

Example 4

In the HOTEL database, the twelfth attribute of each item in the GUESTS file (BILL-AMT) is multivalued, listing several bill totals for each guest. The following item could be set up in the dictionary of the ROOMS file to translate the third multivalue from that attribute:

     BILL
001  A
002  0
003  Amount
004
005
006
007
008  A;(NF:" ":0)(T;X3;;12)
009  R
010  6

This definition retrieves the name of the file using the 'A' function 'NF', and appends a space separator, followed by the contents of attribute 0 as an item ID.

The command:

LIST ROOMS BED-TYPE GUEST-NAME BILL

would then display:

PAGE 1          12:07:13        07 FEB 1994
ROOMS   Bed     Current Guest   Amount
        Type
140     Queen   Lynch   17.00
119     Double  Scott   17.95
147     King    Janson  6.95
428     King    Postma  65.00
309     King    Mendell 78.00
211     King    Lewis   34.88
.
.
.

Example 5

This example shows how, by using the A conversion code, a file name can be dynamically generated. In this way, the same data definition item can be applied to a number of different files (containing yearly archive data, for instance).

The following item is created in a common file called REPOSITORY.

     ITEM
001  A
002  0
003  Product
004  
005  
006  
007  
008  A;(NFF:",CONVERT ":2)(T;X;;4)
009  L
010  6

This definition retrieves the base name of the file using the A function. 'NFF', appends a ",CONVERT " constant section name to the end together with an extra space separator, then finally appends the contents of attribute 2 as an item ID. It therefore translates attribute 2 from the specified file through the CONVERT data-section of the same file and displays attribute 4 of that item.

This common item can then be used to list the contents of different files, provided they have the same format (in this case, provided they have a CONVERT data section). For example

LIST ORDERS ITEM USING REPOSITORY

lists the products in the ORDERS file, and

LIST NEWFILE,1992 ITEM USING REPOSITORY

lists the products in the NEWFILE,1992 file.