MySQL 8.0

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select  '111' REGEXP '(\\w)\\1\\1';

'111' REGEXP '(\w)\1\1'

1

select  '211' REGEXP '(\\w)\\1\\1';

'211' REGEXP '(\w)\1\1'

0

select  '112' REGEXP '(\\w)\\1\\1';

'112' REGEXP '(\w)\1\1'

0