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2.2.5 Operator Invocations

There are three possible syntaxes for an operator invocation:

• expression operator expression (binary infix operator)
• operator expression (unary prefix operator)
• expression operator (unary postfix operator)

where the operator token follows the syntax rules of section 2.1.3 Operators, or is one of the key words AND, OR, and NOT, or is a qualified operator name in the form

OPERATOR(schema.operatorname)

Which particular operators exist and whether they are unary or binary depends on what operators have been defined by the system or the user. section 7 Functions and Operators describes the built-in operators.