- publishing free software manuals
PostgreSQL Reference Manual - Volume 1 - SQL Language Reference
by The PostgreSQL Global Development Group
Paperback (6"x9"), 716 pages
ISBN 0954612027
RRP £32.00 ($49.95)

Sales of this book support the PostgreSQL project! Get a printed copy>>>

6.6 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:

For the “false” state, the following values can be used:

Using the key words TRUE and FALSE is preferred (and SQL-compliant).

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

section 6.6 Boolean Type shows that boolean values are output using the letters t and f.

boolean uses 1 byte of storage.

ISBN 0954612027PostgreSQL Reference Manual - Volume 1 - SQL Language ReferenceSee the print edition