MySQL 的 vsql_boolean 扩展

INSTALL EXTENSION vsql_boolean;

SELECT EXTENSION_NAME
FROM INFORMATION_SCHEMA.EXTENSIONS
WHERE EXTENSION_NAME = 'vsql_boolean';

+----------------+
| EXTENSION_NAME |
+----------------+
| vsql_boolean   |
+----------------+

CREATE TABLE flags (
    id     INT PRIMARY KEY,
    name   VARCHAR(16),
    active STRICTBOOL
);

INSERT INTO flags VALUES
    (1, 'alpha', 'true'),
    (2, 'beta',  'no'),
    (3, 'gamma', 'on'),
    (4, 'delta', '0');

SELECT name, active FROM flags;

+-------+--------+
| name  | active |
+-------+--------+
| alpha | true   |
| beta  | false  |
| gamma | true   |
| delta | false  |
+-------+--------+

SELECT boolean_sum(active) AS enabled, ROUND(boolean_avg(active), 2) AS fraction
FROM flags;

+---------+----------+
| enabled | fraction |
+---------+----------+
|       2 |      0.5 |
+---------+----------+