| PostgreSQL 8.2.6 Documentation | ||||
|---|---|---|---|---|
| Prev | Fast Backward | Chapter 8. Data Types | Fast Forward | Next |
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' |
| '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 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.