Logical Expressions

OQL provide three logical expressions which can take two form each. The logical or operator is || or or. The logical and operator is && or and. The logical not operator is ! or not.

The expression syntax, semantics, associativity and precedence are quite identical to the corresponding C and C++ expressions. Note that the ODMG operator ``||'' denotes the string concatenation.
As for C and C++, the OQL interpreter performs a lazy evaluation:

• expr1 || expr2
  expr2 is not evaluated if expr1 is evaluated to true.
• expr1 && expr2
  expr2 is not evaluated if expr1 is evaluated to false.

General Information
Operators	||
	&&
Type	unary, binary
Syntaxes	expr || expr
	expr or expr
	expr && expr
	expr and expr
	! expr
	not expr
Operand Type	boolean
Result Type	boolean
Functions	logical or
	logical and
	logical not

Expression Examples
expression	result
true || false	true
false || false	false
true && false	false
1 == 2 || 3 == 4	false
1 == 2 || 3 == 3	true
1 == 2 or 3 == 3	true
1 == 2 || "hello" == "hello"	true
(1 == 2 || 2 == 2) && (a = "hello")	returns true if a equals "hello". false otherwise
1 || 3 == 3	raises an error: boolean expected got integer
!3	raises an error: boolean expected got integer
!(1 == 1)	false
not(1 == 1)	false