Operators

Wed, 03/04/2009 - 20:02 |  hdanzl

Operators are symbols and keywords that specify an operation to be performed on one or more value expressions.


Arithmetic operators

The arithmetic operators perform operations on numeric values.

Operator

Symbol

Operation

<addition operator>

+

Addition

<subtraction operator>

-

Subtraction

<multiplication operator>

*

Multiplication

<division operator>

/

Division

Note: The addition (+) and subtraction (-) operators are also used in arithmetic operations on datetime values.

See also: Numeric Value Functions.


Concatenation operators

The concatenation operator is used to concatenate string values.

Operator

Symbol

Operation

<concatenation operator>

||

String concatenation

Note: The arithmetic addition (+) operator can be used as an alternate string concatenation operator.

See also: String Value Functions.


Comparison operators

The comparison operators are used in some predicates to specify comparison tests.

Operator

Symbol

Operation

<equals operator>

=

Equal to

<not equals operator>

<>

Not equal to

<less than operator>

<

Less than

<greater than operator>

>

Greater than

<less than or equals operator>

<=

Less than or equal to

<greater than or equals operator>

>=

Greater than or equal to

Note: The equals sign (=) is also used as an assignment operator.


Boolean operators

The boolean operators are used to combine predicates in search conditions.

Operator

Keyword

Operation

<boolean NOT operator>

NOT

Invert the result of the boolean test

<boolean AND operator>

AND

Test if both predicates are TRUE

<boolean OR operator>

OR

Test if either of the predicates is TRUE

Note: Check the truth tables to see how combined boolean expressions are evaluated.


Assignment operator

The equals sign is used for value assignments.

Operator

Symbol

Operation

<assignment operator>

=

Value assignment

Operator precedence

Operator precedence determines the order in which operations are performed during the execution of a complex value expression with multiple operators.

Operators are evaluated in the following order, ranked from highest to lowest precedence level:

♦ * (multiplication), / (division)
♦ + (addition), - (subtraction)
♦ ||, + (concatenation)
♦ =, <>, <, >, <=, >= (comparison operators)
♦ NOT
♦ AND
♦ OR

Operators on the same precedence level are evaluated left to right based on their position in the value expression.

If a value expression has nested parentheses, the innermost expression is evaluated first.

Tip: Instead of relying on the defined operator precedence, it is recommended to use parentheses to explicitly specify the order of operations in complex value expressions with many operators. All operations inside parentheses are evaluated first to yield a single value before that value is used as an operand in other operations.


Conformance

SQL:2003 standard

NexusDB extensions

-

-

Core SQL

Plus sign as string concatenation operator
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