A
database would not be very efficient if all logical entries had to be accessed when you needed
data from only some of them. SYSTEM 2000 enables you to specify a
where-clause to identify those parts of the database that are relevant to your query or update.
A where-clause consists of the keyword WHERE (or WH) and one or more specific conditions
that values
must meet. Usually, a
condition consists of a
schema item, an operator, and a value or a range of values. For example:
WHERE ACCRUED VACATION EXISTS
WHERE SEX EQ MALE
WHERE BIRTHDAY SPANS 01/01/1949 * 12/31/1949
WHERE STREET ADDRESS CONTAINS /RIM ROCK/You can also combine
conditions by using connector operators to form expressions. For example:
WHERE SKILL TYPE = COBOL AND
YEARS OF EXPERIENCE = 4 For the
SAS/ACCESS interface to SYSTEM 2000, you can include a SYSTEM 2000 where-clause in a
view descriptor to specify selection criteria. In addition to or instead of a SYSTEM 2000 where-clause,
you can specify selection criteria in a SAS program by using a SAS WHERE clause.
Note: The SYSTEM 2000 where-clause
and the WHERE clause in SAS are different. For example, in a SYSTEM
2000 where-clause, the date format (by default) is
MM/DD/YYYY, and you do not have to include single
quotes around character strings.