comparison-operators.rst

psql

Comparison operators

A comparison operator <gloss-operator> tests the relationship between two values and returns a corresponding value of true, false, or NULL.

Table of contents

Basic operators

For simple data types <data-types>, the following basic operators can be used:

Operator	Description
<	Less than
--------	--------------------------
>	Greater than
--------	--------------------------
<=	Less than or equal to
--------	--------------------------
>=	Greater than or equal to
--------	--------------------------
=	Equal
--------	--------------------------
<>	Not equal
--------	--------------------------
!=	Not equal (same as <>)

When comparing strings, a lexicographical comparison is performed:

cr> select name from locations where name > 'Argabuthon' order by name;
+------------------------------------+
| name                               |
+------------------------------------+
| Arkintoofle Minor                  |
| Bartledan                          |
| Galactic Sector QQ7 Active J Gamma |
| North West Ripple                  |
| Outer Eastern Rim                  |
+------------------------------------+
SELECT 5 rows in set (... sec)

When comparing dates, ISO date formats can be used:

cr> select date, position from locations where date <= '1979-10-12' and
... position < 3 order by position;
+--------------+----------+
| date         | position |
+--------------+----------+
| 308534400000 |        1 |
| 308534400000 |        2 |
+--------------+----------+
SELECT 2 rows in set (... sec)

Tip

Comparison operators are commonly used to filter rows (e.g., in the WHERE <sql-select-where> and HAVING <sql-select-having> clauses of a SELECT <sql-select> statement). However, basic comparison operators can be used as value expressions <sql-operator-invocation> in any context. For example:

cr> SELECT 1 < 10 as my_column;
+-----------+
| my_column |
+-----------+
| TRUE      |
+-----------+
SELECT 1 row in set (... sec)

WHERE clause operators

Within a sql_dql_where_clause, the following operators can also be used:

Operator	Description
~	Matches regular expression (case sensitive)
--------------------------	---------------------------------------------------
~*	Matches regular expression (case insensitive)
--------------------------	---------------------------------------------------
!~	Does not match regular expression (case sensitive)
--------------------------	---------------------------------------------------
!~*	Does not match regular expression (case insensitive)
--------------------------	---------------------------------------------------
sql_dql_like	Matches a part of the given value
--------------------------	---------------------------------------------------
sql_dql_not	Negates a condition
--------------------------	---------------------------------------------------
sql_dql_is_null	Matches a null value
--------------------------	---------------------------------------------------
sql_dql_is_not_null	Matches a non-null value
--------------------------	---------------------------------------------------
ip << range	True if IP is within the given IP range (using CIDR notation)
--------------------------	---------------------------------------------------
x BETWEEN y AND z	Shortcut for x >= y AND x <= z

• sql_array_comparisons
• sql_subquery_expressions