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DATA, INPUT, and PROMPT
Transact can perform a number of different data entry functions in
character mode with the use of the DATA, INPUT, and PROMPT verbs.
The DATA and PROMPT verbs will prompt the user for a response to a prompt
string or item name. Transact will validate the data and prompt the user
again if any errors are detected. The major difference between the DATA
and PROMPT verbs is the registers that are updated. The PROMPT verb will
add the item to the list register, whereas the DATA verb will only update
an item already on the list register. Depending on the modifier used for
each verb, values would also be placed in the data, argument, match,
and/or update registers. The input value for the DATA and PROMPT verbs
is usually used for subsequent file and data set operations.
The INPUT verb will prompt the user for a response to a prompt string.
The value will be placed in the INPUT register. The INPUT verb is used
to test a user response.
Special characters that can be entered by the user in response to the
prompt are discussed later in this chapter. To get additional
information and examples of the DATA, INPUT, and PROMPT verbs, see
Chapter 8. A discussion of the use of the MATCH modifier with the DATA
and PROMPT verbs follows.
Responding to a MATCH Prompt
The MATCH modifier, available with the PROMPT, DATA, and LIST verbs,
provides a powerful mechanism for specifying record selection criteria.
The response to a prompt issued by the PROMPT or DATA verb using the
MATCH modifier is set up in the match register. Transact can use it in
subsequent file or data set accesses. It provides a mechanism by which
to specify at run time which records to access.
With native language support, the usage of the specified language is
reflected in the relational operators, the connectors, and the range
indicator (such as, "TO"). See "Native Language Support" in Appendix E
for more information.
The response to the prompt can take the following general format:
{[relation] value1} {[relation] value2}
{ } [connector { } ]...
{value1 TO value2 } {value3 TO value4 }
Where:
relation Is a relational operator for a condition that is
other than equal; use one of the following:
NE - not equal to (< >)
LT - less than (<)
LE - less than or equal to (<=)
GT - greater than (>)
GE - greater than or equal to (>=)
value A numeric value or a partial string specification. A
string with embedded blanks must be enclosed in
quotation marks.
TO Specifies a range of values bounded by the value
preceding and the value following TO.
connector A logical connector that is one of the following:
AND Specifies that the record accessed must
contain both the value before and the
value after this operator.
OR Specifies that the record accessed must
contain either the value before or the
value after this operator.
The precedence of these connectors is
AND then OR.
To illustrate this syntax, assume the program contains the following
PROMPT(MATCH) statement:
PROMPT(MATCH) ITEM1 ("Enter match criteria for ITEM1");
When executed, this statement adds the item name, ITEM1, to the list
register and issues the specified prompt. It then sets up the match
register with criteria entered by the user. For example:
Enter match criteria for ITEM1> GE 500 AND LE 1000
This response sets up the match register with two criteria, as shown
below:
__________________________________________________________________________
| |
| |
| ITEM1 ITEM1 |
| ( equal to OR greater than ) AND ( less than OR equal to )|
| 500 500 1000 1000 |
| |
__________________________________________________________________________
To further illustrate this syntax, the following examples are all legal
responses to prompts issued by DATA(MATCH) or PROMPT(MATCH) statements:
> 20 TO 30
This response sets up the match register to accept any value for the
match item that is between 20 and 30 inclusive. Note that the following
response gives identical results:
> GE 20 AND LE 30
The following response sets up the match register to accept either the
value "LAX" or "CGY":
> LAX OR CGY
This next response sets up the match register to accept values beginning
with "REG" or values beginning with "SAS" and containing the value "CITY"
in any position:
> REG^ OR SAS^ AND CITY^^
If you want to include one of the standard delimiters, comma, or equals,
within a value, you must enclose the value in quotes; or you must specify
another delimiter with a SET(DELIMITER) statement. For example, you
could respond with:
> "San Diego, California"
This response ensures that the comma is included in the match register
specification.
These examples illustrate how you can set up the match register with
responses to DATA(MATCH) or PROMPT(MATCH) statements. You can also set
up the match register in your program with SET(MATCH) statements. Using
SET(MATCH), you can set up only one selection specification at a time,
and you must also make sure the values used in the match criteria are
already in the data register. For example, the following four statements
place the same criteria in the match register as the response "A OR B" to
the prompt issued by a DATA(MATCH) CREDIT statement.
LET (CREDIT) = A;
SET(MATCH) LIST (CREDIT);
LET (CREDIT) = B;
SET(MATCH) LIST (CREDIT);