| SQR Arrays | KEVIN RESCHENBERG
06-13-2005 |
Some SQR programmers use arrays extensively while others
rarely if ever use them. If you're like me, the first time
you saw arrays in an SQR program, you were probably
wondering how they came up with THAT syntax! SQR arrays
are a little different from those in other languages.
But they do offer a good deal of flexibility.
Arrays can be either one-dimensional, two-dimensional,
or something like what other languages would call arrays of "records"
or user-defined types. One array can even be a combination
of these—for example, several two-dimensional arrays.
Arrays are defined with the CREATE-ARRAY statement, which
defines the size (number of rows) and columns ("fields")
in the array.
create-array
name=CustomerBalances
size=1000
field=CustomerID:char
field=Name:char
field=Balance:number
This array has up to 1000 rows
(numbered from 0 to 999), and 3 columns containing
dissimilar types of data. (Note that all arrays are
global in scope and are created before the
program begins to run. Therefore, CREATE-ARRAY cannot
be bypassed by an IF, for example.)
There are also two completely different ways of
referencing array elements, although the first seems
to be the most common:
put '001' 'John Doe' 123.45
into CustomerBalances(0) CustomerID Name Balance
! Or use this syntax:
let CustomerBalances.CustomerID(0) = '001'
let CustomerBalances.Name(0) = 'John Doe'
let CustomerBalances.Balance(0) = 123.45
We can then read the array data using
either of these types of syntax:
get $CustID $Name #Balance
from CustomerBalances(0) CustomerID Name Balance
! Or use this syntax:
let $CustID = CustomerBalances.CustomerID(0)
if CustomerBalances.Balance(0) > 0
...
The first type of syntax (GET/PUT)
seems to be used more often in PeopleSoft
programs and is actually sort of a shortcut. The other
type of syntax lets us use array elements directly if
we want without moving them to or from regular variables.
We can build two-dimensional arrays by specifying a number
of occurrences for a field. For example, if we wanted to
store balances by month:
create-array
name=CustomerBalances
size=1000
field=CustomerID:char
field=Name:char
field=Balance:number:12
The only change here is the addition of
the "12" for the Balance field. This gives us 12 Balance
fields on each row of the array. The first balance for
the first customer is then available as
CustomerBalances.Balance(0,0):
let CustomerBalances.Balance(0,0) = 100
let CustomerBalances.Balance(0,1) = 200
Using this example and after filling
some of the fields with data, here is how this array
can be visualized (as shown in
SP Debugger for SQR):
Although they may seem strange at first, SQR arrays give
us a lot of flexibility and can be used to simplify
our programs or improve their performance.
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