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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:

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

 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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