Operators
In Chapter 3, operators are defined syntactically as tokens that are used to perform operations on values (e.g., constants, or identifiers), and return the results of those operations. In addition to these syntactic character symbols, there are some SQL keywords that are considered operators due to their effect on values in a SQL statement. Throughout this section, both these symbols and keywords will be referred to as operators.
The function of each operator is highly dependent on its context. Applications of operators range from performing mathematical operations and concatenating character strings, to performing a wide variety of comparisons yielding Boolean results. This section describes the general usage of operators in SQL, with successive sections on the following families of operators:
Character string
Numeric
Logical
Note
For an up-to-date and complete list of PostgreSQL supported operators, you can use
psqlâs \do
slash command to view a list of available
operators. Understand that many of the listed operators are PostgreSQL-specific, and therefore
may not exist in other SQL-capable databases implementations.
Following the discussions of the various types of operators, youâll find information on
dealing with NULL
values in expressions, and on the order in which operators
are evaluated.
Using Operators
Operators operate on either a single value or a pair of values. ...
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