Boolean

Overview

BOOLEAN (alias BOOL) represents TRUE or FALSE and always uses one byte of storage. Numeric and string inputs automatically coerce to boolean values when possible.

Input Type	Converts to TRUE	Converts to FALSE	Notes
Numeric	Any non-zero	0	Negative numbers convert to TRUE.
String	TRUE	FALSE	Case-insensitive; other text fails to cast.

Examples

SELECT
  0::BOOLEAN            AS zero_is_false,
  42::BOOLEAN           AS nonzero_is_true,
  'True'::BOOLEAN       AS string_true,
  'false'::BOOLEAN      AS string_false;

Result:

┌───────────────┬──────────────────┬───────────────┬────────────────┐
│ zero_is_false │ nonzero_is_true  │ string_true   │ string_false   │
├───────────────┼──────────────────┼───────────────┼────────────────┤
│ false         │ true             │ true          │ false          │
└───────────────┴──────────────────┴───────────────┴────────────────┘

-- Casting unsupported text raises an error.
SELECT 'yes'::BOOLEAN;

Result:

ERROR 1105 (HY000): QueryFailed: [1006]cannot parse to type `BOOLEAN` while evaluating function `to_boolean('yes')` in expr `CAST('yes' AS Boolean)`