MySQL 8.0 has JSON_TABLE. These is also available in Oracle, DB2. (PostgreSQL has a patch under development but it is not in the 12th release?)
- MySQL: https://dev.mysql.com/doc/refman/8.0/en/json-table-functions.html
- SQL Standard: This page https://modern-sql.com/blog/2017-06/whats-new-in-sql-2016
has a link to http://standards.iso.org/ittf/PubliclyAvailableStandards/c067367_ISO_IEC_TR_19075-6_2017.zip
which in section 5.3.4 has a specification for JSON_TABLE function.