Using &NDBSCAN Statements › SQL-like Operators

SQL-like Operators

Scans can perform some SQL-like functions:

• The IS [NOT] NULL operators provide equivalent functionality to the PRESENT and ABSENT operators, but are SQL-compatible.
• The [NOT] BETWEEN operators are equivalent to the =value:value and p=value:value operators, and are SQL-compatible.
• The [NOT} IN operators are equivalent to the [p]= value-list operators, and are SQL-compatible.
• The SELECT clause lets you perform sub-selects, where a list of values derived from a set of records matching some criteria can be used as input to an outer-level scan.

The EXISTS operator uses the fact that at least one record exists in the inner select/scan to determine truth or falsity.

A correlated select is possible. This causes an inner scan to be re-executed once for each other outer record that passed part of a scan. The outer record field values are used in the inner scan as comparison values.