Expressions
232
address
"date hired"
"salary"."date paid"
$ For more information on identifiers, see "Identifiers" on page 223.
Subqueries in expressions
A subquery is a SELECT statement enclosed in parentheses. The SELECT
statement must contain one and only one select list item. When used as an
expression, a subquery is generally allowed to return only one value.
A subquery can be used anywhere that a column name can be used. For
example, a subquery can be used in the select list of another SELECT
statement.
$ For other uses of subqueries, see "Subqueries in search conditions" on
page 240.
IF expressions
The syntax of the IF expression is as follows:
IF
condition
THEN
expression1
[ ELSE
expression2
]
ENDIF
This expression returns the following:
♦ If condition is TRUE, the IF expression returns expression1.
♦ If condition is FALSE, the IF expression returns expression2.
♦ If condition is FALSE, and there is no expression2, the IF expression
returns NULL.
♦ If condition is NULL, the IF expression returns NULL.
$ For more information about TRUE, FALSE and UNKNOWN
conditions, see "NULL value" on page 260, and "Search conditions" on
page 239.
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