Alternatives to the EACH keyword
- Last Updated: March 30, 2020
- 1 minute read
- OpenEdge
- Version 12.2
- Documentation
Alternatives to the EACH keyword
Sometimes you just want a single record from a table.
In that case, you can use the FIRST or LAST keyword
in place of EACH, or possibly use no qualifier
at all. For example, if you want to retrieve Orders and
their Customers instead of the other way
around, you can leave out the keyword EACH in the Customer phrase,
because each Order has only one Customer:
|
When you use this form, make sure that there is never more than one record satisfying the join. Otherwise, you get a run-time error telling you that there is no unique match.
If you'd like to see just the first Order for
each Customer in New Hampshire, you can use
the FIRST qualifier to accomplish that:
|
Be careful, though. This form might not always yield the result you expect, because you have to consider just what is the first Order of a Customer? The AVM uses an index of the Order table to traverse the rows.