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REEXTRACT STRUCTURE can be used to do a second extract on a list of structure records you previously extracted. This allows for increasingly specific records to be chosen through a series of REEXTRACTs.
REEXTRACT does an extract on the list of records previously extracted. struc_name is the structure name associated with an open structure.
END EXTRACT marks the end of the REEXTRACT construct. REEXTRACT operates the same as EXTRACT. However, REEXTRACT operates on a previously extracted list.
Extract operations by key cannot be performed with REEXTRACT. |
15.7.10 EXTRACT STRUCTURE: APPEND
EXTRACT STRUCTURE struc_name: APPEND
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| Example 15-22 APPEND option in EXTRACT STRUCTURE |
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open structure detail: name 'sheerpower:samples\detail'
set structure detail: extracted 0
extract structure detail, field lineid : &
key '10301001' to '10302000', append
sort by detail(prodnbr)
sort by detail(invnbr)
end extract
extract structure detail, field lineid : &
key '10311001' to '10312000', append
sort by detail(prodnbr)
sort by detail(invnbr)
end extract
print 'Prod'; tab(7); 'Line ID'; tab(17); 'Quantity'
for each detail
print detail(prodnbr); tab(7); detail(lineid); &
tab(17); detail(qty)
next detail
end
Prod Line ID Qty
22800 10301-002 2
22800 10301-004 1
22800 10301-006 2
24100 10311-003 1
24200 10301-003 1
24200 10311-009 1
28400 10311-001 2
28800 10301-009 2
28800 10311-002 9
28800 10311-005 1
28800 10311-006 1
31020 10301-005 1
31040 10311-010 2
31150 10301-001 1
31150 10301-008 8
31150 10311-004 1
31150 10311-008 1
33090 10301-007 2
33090 10311-007 1
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The EXTRACT STRUCTURE: APPEND statement adds records to the last collection of extracted records rather than creating a new collection.
ASK STRUCTURE struc_name: struc_option [num_var | str_var]
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The ASK STRUCTURE statement is used to ask about various device and structure characteristics from within your programs. struc_name is the name of a structure whose characteristics are being asked about. struc_option can be any of the structure options available. The options are explained in the following sections.
15.8.1 ASK STRUCTURE FIELD: item
ASK STRUCTURE struc_name, FIELD field_expr: item var
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| Example 15-23 ASK STRUCTURE FIELD: item |
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open structure cl: name 'sheerpower:samples\client'
ask structure cl: fields num_fields
for i = 1 to num_fields
clear
ask structure cl, field #i: description b$
ask structure cl, field #i: prompt a$
ask structure cl, field #i: position a%
ask structure cl, field #i: length b%
ask structure cl, field #i: heading f$
ask structure cl, field #i: printmask c$, &
screenmask d$, &
help e$
print at 5,5: ''
print 'Description : '; b$
print 'Prompt : '; a$
print 'Position : '; a%
print 'Field length :' ; b%
print 'Rpt. heading : '; f$
print 'Print mask : '; c$
print 'Screen mask : '; d$
print 'Help : '; e$
delay
next i
close structure cl
end
Description : Client ID number
Prompt : Client ID number
Position : 1
Field length : 5
Rpt. heading : CLNT,ID
Print mask : >####
Screen mask : digits:#####
Help : Client ID number
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The FIELD option allows you to get information about a specific field in a structure. struc_name is the name of the structure. field_expr is the field you are inquiring about. item specifies what type of information you are asking. The information is stored in the variable specified.
The following sections provide more information on what you can use for field_expr and on the various field items.
The ITEM information is created when the SETUP routine is used to define the field. You can refer to Chapter 16, Database Setup for information on defining fields. |
The field_expr used in the ASK STRUCTURE FIELD: item statement can be either a constant or a string or numeric expression.
A string constant can be used to specify the field name. To use a string constant, just enter the field name, without quotes. SheerPower will then use the string constant as the field name:
ASK STRUCTURE sheerpower:samples\CLIENT, FIELD LAST: DESCRIPTION A$
/
the field is specified by its field name
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You can also specify a field name with an expression. To use an expression, precede the expression with a pound sign (#). The pound sign tells SheerPower that the following characters are an expression, not the field name. If a pound sign is not included SheerPower will interpret the characters as a field name.
ASK STRUCTURE CL, FIELD #FIELDNAME$: DESCRIPTION A$
/
the field is specified by the value of the variable FIELDNAME$
ASK STRUCTURE CL, FIELD #FIELDNUM: DESCRIPTION A$
/
the field is specified by the value of the variable FIELDNUM
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This example shows how to access the actual field data using field expressions.
| Example 15-24 Field expressions in ASK STRUCTURE FIELD |
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open structure cl: name 'sheerpower:samples\client'
do
clear
print at 1, 1:;
ask_fields
if _back or _exit then exit do
show_data
loop
close structure cl
stop
routine ask_fields
do
if _error then set error off
print 'Field List: '; &
'ID, LAST, FIRST, MIDDLE, STREET, CITY, STATE, ZIP, PHONE'
print
line input 'Select fields to display': field_list$
if _back or _exit then exit do
for f = 1 to elements(field_list$)
field$ = element$(field_list$, f)
ask structure cl, field #field$: number z
if z = 0 then
message error: 'Illegal field: '; field$
end if
next f
loop while _error
end routine
routine show_data
print
extract structure cl
for f = 1 to elements(field_list$)
field$ = element$(field_list$, f)
print cl(#field$),
next f
print
end extract
delay
end routine
end
Field List: ID, LAST, FIRST, MIDDLE, STREET, CITY, STATE, ZIP, PHONE
Select fields to display? last,first,phone
Smith Sam (809) 555-8789
Kent Keith (619) 967-5021
Johnson Paul (619) 489-5551
Waters Wayne (619) 564-1231
Rodrigues Homero ( ) - 0
Donaldson George ( ) - 0
Errant Earl (408) 844-7676
Abott Al (202) 566-9892
Brock Bud (218) 555-4322
Cass Cathy (619) 743-8582
Porter Pete (619) 778-6709
Derringer Dale (818) 223-9014
Farmer Fred (305) 552-7872
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ASK STRUCTURE struc_name, FIELD field_name: ACCESS str_var
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ACCESS retrieves the access (read and write) rules for the specified field. This information tells if the field can be read and written to. N is normal--meaning the field can be read and written to if the structure is also "N"ormal. Depending on whether security levels have been set on the structure and/or field, the letter can be in the range of A thru Z. SheerPower defaults to N when the structure is created and fields are defined.
| Example 15-25 ACCESS - field definition item |
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open structure inv: name 'sheerpower:samples\invoice', access input ask structure inv, field custnbr: access x$ print x$ close structure inv end READ:N, WRITE:N |
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