DELETE

The DELETE command deletes specified data records and all key index structure associated with those records.

Syntax:
                DELETE/options collection [tablename]

                                Notation standards              Options Answers

Options:
                X             -Suppress the command response
                Y             -Do not alter the command answer cells

Answers:
                Ctl.Ans1                -Number of records deleted
                Ctl.Ans2                -Zero
                Ctl.Ans3                -Zero

Notes:
The subset you isolate determines the records to be deleted.

Suppose you want to delete all the SALES records for the year 1980.

                                FIND A SALES WHERE YR=80
                                DELETE A SALES

In this example, you isolate specific records from the SALES table into collection A and then delete them.

But now suppose you want to delete all records for customers number AX0021. This customer number appears in more than one table.

                                FIND A WHERE CUST# = AX0021
                                DELETE A

In this case, you isolate all occurrences of CUST# AX0021 (that is, from all tables in the data base in which it occurs) into collection A, and then delete them. Observe that the first DELETE example is table specific. The second example is global.

Be very careful when you are doing global deletes. Be sure you know the status of each tables portion of the collection, because all isolated records in all portions of the collection are going to be deleted when the delete is global, that is, when it is not table specific. If you mean to be deleting records from just one table, it is always safest to be specific in the DELETE command, and mention that table name. For an example of what not to do, consider the following sequence:

                                FIND A SALES WHERE YR=80                                        DO NOT DO THIS
                                DELETE A                                                                             DO NOT DO THIS

DO NOT DO THIS! Because the collection was not CLEARed at the beginning of this sequence, and the FIND was table specific, you do not know the status of the other portions of this collection. The DELETE is not specific, so it will delete everything it finds in all portions of collection A. This could be disaster.

It was correct to do a global DELETE in the example above that involved the CUST#, because in that example the query was global (the FIND did not mention a table name) so the status of the entire collection is known. Only the records you want to delete are found, and any table's portion where the set selection criterion CUST# = AX0021 is not true is set to zero.

Don't confuse DELETE with ERASE, which is used to erase files by referring to their file names.