Comparison operators

A comparison 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, 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)

When comparing Geo Shapes, topological comparison is used. Topological equality means that the geometries have the same dimension, and their point-sets occupy the same space. This means that the order of vertices may be different in topologically equal geometries:

cr> SELECT 'POLYGON (( 0 0, 1 0, 1 1, 0 1, 0 0))'::GEO_SHAPE = 'POLYGON (( 1 0, 1 1, 0 1, 0 0, 1 0))'::GEO_SHAPE as res;
+------+
| res  |
+------+
| TRUE |
+------+
SELECT 1 row in set (... sec)

Geometry collections, containing only linestrings, points or polygons are normalized to MultiLineString, MultiPoint and MultiPolygon. Hence, geometry collection of points is equal to a MultiPoint with the same points set:

cr> select 'MULTIPOINT ((10 40), (40 30), (20 20))'::GEO_SHAPE = 'GEOMETRYCOLLECTION (POINT (10 40), POINT(40 30), POINT(20 20))'::GEO_SHAPE;
+------+
| true |
+------+
| TRUE |
+------+
SELECT 1 row in set (... sec)

Tip

Comparison operators are commonly used to filter rows (e.g., in the WHERE and HAVING clauses of a SELECT statement). However, basic comparison operators can be used as value expressions 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 WHERE clause, the following operators can also be used:

Operator

Description

~ , ~* , !~ , !~*

See Regular expressions

LIKE (ILIKE)

Matches a part of the given value

NOT

Negates a condition

IS NULL

Matches a null value

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

See also