Comparison condition - Amazon Redshift
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# Comparison condition

Comparison conditions state logical relationships between two values. All comparison conditions are binary operators with a Boolean return type. Amazon Redshift supports the comparison operators described in the following table:

Operator Syntax Description
< `a < b` Value a is less than value b.
> `a > b` Value a is greater than value b.
<= `a <= b` Value a is less than or equal to value b.
>= `a >= b` Value a is greater than or equal to value b.
= `a = b` Value a is equal to value b.
<> or != `a <> b or a != b` Value a is not equal to value b.
ANY | SOME `a = ANY(subquery)` Value a is equal to any value returned by the subquery.
ALL `a <> ALL or != ALL (subquery))` Value a is not equal to any value returned by the subquery.
IS TRUE | FALSE | UNKNOWN `a IS TRUE` Value a is Boolean TRUE.

## Usage notes

= ANY | SOME

The ANY and SOME keywords are synonymous with the IN condition, and return true if the comparison is true for at least one value returned by a subquery that returns one or more values. Amazon Redshift supports only the = (equals) condition for ANY and SOME. Inequality conditions are not supported.

###### Note

The ALL predicate is not supported.

<> ALL

The ALL keyword is synonymous with NOT IN (see IN condition condition) and returns true if the expression is not included in the results of the subquery. Amazon Redshift supports only the <> or != (not equals) condition for ALL. Other comparison conditions are not supported.

IS TRUE/FALSE/UNKNOWN

Non-zero values equate to TRUE, 0 equates to FALSE, and null equates to UNKNOWN. See the Boolean type data type.

## Examples

Here are some simple examples of comparison conditions:

``````a = 5
a < b
min(x) >= 5
qtysold = any (select qtysold from sales where dateid = 1882``````

The following query returns venues with more than 10000 seats from the VENUE table:

``````select venueid, venuename, venueseats from venue
where venueseats > 10000
order by venueseats desc;

venueid |           venuename            | venueseats
---------+--------------------------------+------------
83 | FedExField                     |      91704
6 | New York Giants Stadium        |      80242
78 | INVESCO Field                  |      76125
69 | Dolphin Stadium                |      74916
67 | Ralph Wilson Stadium           |      73967
76 | Jacksonville Municipal Stadium |      73800
89 | Bank of America Stadium        |      73298
72 | Cleveland Browns Stadium       |      73200
86 | Lambeau Field                  |      72922
...
(57 rows)``````

This example selects the users (USERID) from the USERS table who like rock music:

``````select userid from users where likerock = 't' order by 1 limit 5;

userid
--------
3
5
6
13
16
(5 rows)
``````

This example selects the users (USERID) from the USERS table where it is unknown whether they like rock music:

``````select firstname, lastname, likerock
from users
where likerock is unknown
order by userid limit 10;

firstname | lastname | likerock
----------+----------+----------
Rafael    | Taylor   |
Barry     | Roy      |
Tamekah   | Juarez   |
Mufutau   | Watkins  |
Naida     | Calderon |
Anika     | Huff     |
Bruce     | Beck     |
Mallory   | Farrell  |
Scarlett  | Mayer    |
(10 rows``````

## Examples with a TIME column

The following example table TIME_TEST has a column TIME_VAL (type TIME) with three values inserted.

``````select time_val from time_test;

time_val
---------------------
20:00:00
00:00:00.5550
00:58:00``````

The following example extracts the hours from each timetz_val.

``````select time_val from time_test where time_val < '3:00';
time_val
---------------
00:00:00.5550
00:58:00``````

The following example compares two time literals.

``````select time '18:25:33.123456' = time '18:25:33.123456';
?column?
----------
t``````

## Examples with a TIMETZ column

The following example table TIMETZ_TEST has a column TIMETZ_VAL (type TIMETZ) with three values inserted.

``````select timetz_val from timetz_test;

timetz_val
------------------
04:00:00+00
00:00:00.5550+00
05:58:00+00``````

The following example selects only the TIMETZ values less than ```3:00:00 UTC```. The comparison is made after converting the value to UTC.

``````select timetz_val from timetz_test where timetz_val < '3:00:00 UTC';

timetz_val
---------------
00:00:00.5550+00``````

The following example compares two TIMETZ literals. The time zone is ignored for the comparison.

``````select time '18:25:33.123456 PST' < time '19:25:33.123456 EST';

?column?
----------
t``````