William Wu writes:

> One piece of data was saved twice because of quickly hitting ENTER key
> twice almost at the same time, and it seems that those two transactions
> formed a circle pointing to each other.

How is it that you know they "form a circle?"

If the forward pointers of each pointed to the other, then using any tool
to find the data would result in an infinite loop (because end-of-chain
is never reached), unless Image has a mechanism to detect this.

> How to break the circle and delete the duplicate data by using QUERY/3000?

In general, if you have two identical records in a set, you can delete
one of them via Query as follows:

        1. FIND the records using whatever is necessary to isolate
           the duplicates, e.g.,

                find cust-num=123 AND txn-num=456 AND product-num=3000

        2. REPORT ALL to verify that these are really the records
           you expected

        3. SUBSET the result using one of the values from (1),
           but limiting the selection by the number of records to delete:

                subset #limit=1; cust-num=123

        4. DELETE

If, on the other hand, you really do have a "circle," then I trust
you have one of the third-party database maintenance tools.  Even
if you don't, give one of the vendors (Adager and Bradmark come to
mind) a call.  Predictably (thank goodness), they're at Adager.com
and Bradmark.com, respectively.

--Glenn