Special functions (special_function) are special functions which are not restricted to specific data types.
Syntax
<special_function> ::= <case_function> | DECODE(<check_expression>,<search_and_result_spec>,...[,<default_expression>]) | GREATEST(<expression>,<expression>,...) | LEAST(<expression>,<expression>,...) | VALUE(<expression>,<expression>,...) <case_function> ::= <simple_case_function> | <searched_case_function> <check_expression> ::= <expression> <search_and_result_spec> ::= <search_expression>,<result_expression> <default_expression> ::= <expression> <search_expression> ::= <expression> <result_expression> ::= <expression>
A distinction is made between simple and general CASE functions.