The program below creates a table, adds three records, one of which is deleted. The table is then indexed, and the COUNT command is issued, so that the number of visible rows is shown in a message box.
Before you run it, examine the source code, and try to guess what the COUNT line will report. (Hint: think carefully!)
Once you’ve made your guess, type
this in Command window:
modify command dQuiz1 |
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Paste the code below into the program
editor, and press F2 to run it. You may be surprised.
// dQuiz1.prg set deleted on close tables if file("Quiz.dbf") delete table Quiz endif create table "Quiz.dbf" ( Name char(10), City char(10) ) use Quiz exclusive append blank replace Name with 'Paul', City with 'London' append blank replace Name with 'Dan', City with 'Montreal' delete // Delete record number 2. append blank replace Name with 'Peter', City with 'Montreal' index on City tag City unique count // What will it report? |
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Click here for the answer and an explanation.