How to be sure that only one record is taken into account at a given stage of the query? - openedge

Question

I wonder how exactly the "queries" for each and first work.
lets say I have some tables A, B, C and D.
How many records will I find if I use sth like:
first B,
each C,
first D:
<block>
end.
1*|C|*1? [assuming there will be C that has some relation with B, etc]
And then I have sth like this:
for each A,
first B,
/*-----------------------*/
each C,
first D:
<block>
end.
How can I make sure to have the same complexity after this change? (B has now relation with A and there will be some where statements) Will it be |A|*1*|C|*1? And If I want to have the same complexity as before is there anything I can add there?
Example of the problem
define temp-table ttA no-undo
field mainID as character format "x(20)"
field foreignKey as character format "x(20)"
index idx_mainID is unique primary mainID
.
define temp-table ttB no-undo
field mainID as character format "x(20)"
field foreignKey as character format "x(20)"
index idx_mainID is unique primary mainID
.
define temp-table ttC no-undo
field mainID as character format "x(20)"
field foreignKey as character format "x(20)"
index idx_mainID is unique primary mainID
.
define temp-table ttD no-undo
field mainID as character format "x(20)"
field foreignKey as character format "x(20)"
index idx_mainID is unique primary mainID
.
DEFINE VARIABLE viCounterA as integer no-undo.
DEFINE VARIABLE viCounterB as integer no-undo.
DEFINE VARIABLE viCounterC as integer no-undo.
DEFINE VARIABLE viCounterD as integer no-undo.
DEFINE VARIABLE viTotal as integer no-undo.
DEFINE VARIABLE viTotal2 as integer no-undo.
assign
viCounterA = 0
viCounterB = 0
viCounterC = 0
viCounterD = 0
viTotal = 0
viTotal2 = 0
.
DEFINE VARIABLE vcAID as character no-undo.
DO viCounterA = 1 TO 9:
vcAID = "A0" + STRING(viCounterA).
create ttA.
ttA.mainID = vcAID.
ttA.foreignKey = "".
DEFINE VARIABLE vcBID as character no-undo.
DO viCounterB = 1 TO 9:
vcBID = vcAID + "B0" + STRING(viCounterB).
create ttB.
ttB.mainID = vcBID.
ttB.foreignKey = vcAID.
DEFINE VARIABLE vcCID as character no-undo.
DO viCounterC = 1 TO 9:
vcCID = vcBID + "C0" + STRING(viCounterC).
create ttC.
ttC.mainID = vcCID.
ttC.foreignKey = vcBID.
DEFINE VARIABLE vcDID as character no-undo.
DO viCounterD = 1 TO 9:
vcDID = vcCID + "D0" + STRING(viCounterD).
create ttD.
ttD.mainID = vcDID.
ttD.foreignKey = vcCID.
END.
END.
END.
END.
/* DISPLAY V1 */
for first ttB,
each ttC where ttC.foreignKey = ttB.mainID,
first ttD where ttD.foreignKey = ttC.mainID:
viTotal = viTotal + 1.
display
viTotal
ttD.mainID
.
end.
/* DISPLAY V2 */
for each ttA where ttA.mainID = "A01" or ttA.mainID = "A03",
first ttB where ttB.foreignKey = ttA.mainID,
each ttC where ttC.foreignKey = ttB.mainID,
first ttD where ttD.foreignKey = ttC.mainID:
viTotal2 = viTotal2 + 1.
display
viTotal2
ttD.mainID
.
end.
display
viTotal
viTotal2
.

Answer 1

It will be the same as:
define variable i as integer no-undo.
define variable j as integer no-undo.
define variable k as integer no-undo.
for each A no-lock:
i = i + 1.
for first B no-lock:
j = j + 1.
for each C no-lock where C.something = B.something:
k = k + 1.
display i j k.
end.
end.
end.