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CREATE TABLE t (j LONGTEXT);
INSERT INTO t (j) VALUES ('{"a":"1"}');
INSERT INTO t (j) VALUES ('{"b":"2"}');
INSERT INTO t (j) VALUES ('{"c":"0", "d":"0"}');
INSERT INTO t (j) VALUES ('{"c":"1", "d":"1"}');
SELECT DISTINCT `Key`
FROM t,
JSON_TABLE(
JSON_KEYS(t.j),
'$[*]'
COLUMNS(
`Key` VARCHAR(10) PATH "$"
)
) d
| Key |
|---|
| a |
| b |
| c |
| d |