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Historical version. PostgreSQL 8.4 reached end of support in July 2014. See the current version for supported releases.

8.6. Boolean Type

PostgreSQL provides the standard SQL type boolean. boolean can have one of only two states: "true" or "false". A third state, "unknown", is represented by the SQL null value.

Valid literal values for the "true" state are:

TRUE
't'
'true'
'y'
'yes'
'on'
'1'
For the "false" state, the following values can be used:
FALSE
'f'
'false'
'n'
'no'
'off'
'0'
Leading or trailing whitespace is ignored, and case does not matter. The key words TRUE and FALSE are the preferred (SQL-compliant) usage.

Example 8-2. Using the boolean type

CREATE TABLE test1 (a boolean, b text);
INSERT INTO test1 VALUES (TRUE, 'sic est');
INSERT INTO test1 VALUES (FALSE, 'non est');
SELECT * FROM test1;
 a |    b
---+---------
 t | sic est
 f | non est

SELECT * FROM test1 WHERE a;
 a |    b
---+---------
 t | sic est

Example 8-2 shows that boolean values are output using the letters t and f.

boolean uses 1 byte of storage.

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