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An expression is a statement that can be evaluated to return values.
expression:
case-expression
| constant
| [correlation-name.]column-name
| - expression
| expression operator expression
| ( expression )
| function-name ( expression, ... )
| if-expression
| special value
| ( subquery )
| variable-name
case-expression:
CASE expression
WHEN expression
THEN expression,...
[ ELSE expression ]
END
alternative form of case-expression:
CASE
WHEN search-condition
THEN expression, ...
[ ELSE expression ]
END
constant:
integer | number | string | host-variable
special-value:
CURRENT { DATE | TIME | TIMESTAMP }
| NULL
| SQLCODE
| SQLSTATE
| USER
if-expression:
IF condition
THEN expression
[ ELSE expression ]
ENDIF
operator:
{ + | - | * | / | || | % }
Expressions are used in many different places.
Expressions are formed from several different kinds of elements. These are discussed in the sections on functions and variables. See SQL Functions, and Variables.
You must be connected to the database in order evaluate expressions.
None.
For other differences, see the separate descriptions of each class of expression, in the following sections.
Constants in expressions
Column names in expressions
Subqueries in expressions
IF expressions
CASE expressions
Compatibility of expressions