7.5. Boolean Type

Table 7-15. Boolean Type

Name	Aliases	Description
`BOOLEAN`	BIT	logical boolean (true/false)

EnterpriseDB 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'

'1'

For the "false" state, the following values can be used:

FALSE

'f'

'false'

'n'

'no'

'0'

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

Example 7-1. 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 7-1 shows that BOOLEAN values are output using the letters t and f.

Tip: Values of the BOOLEAN type cannot be cast directly to other types (e.g., CAST (boolval AS integer) does not work). This can be accomplished using the CASE expression: CASE WHEN boolval THEN 'value if true' ELSE 'value if false' END. See also Section 8.10.

BOOLEAN uses 1 byte of storage.

Note: For more information on supported datatypes missing from the above chapter, please refer to PostgreSQL's documentation.