Version 6.3 (Released March 1998)

Subselects with EXISTS, IN, ALL, and ANY keywords (Vadim, Bruce, and Thomas).

Added SQL-92 “constants” CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP, and CURRENT_USER.

Modified constraint syntax to be SQL-92–compliant.

Implemented SQL-92 PRIMARY KEY and UNIQUE clauses using indices.

Recognized SQL-92 syntax for FOREIGN KEY.

Allowed NOT NULL UNIQUE constraint clause (each allowed separately before).

Allowed Postgres-style casting (::) of nonconstants.

Added support for SQL3 TRUE and FALSE Boolean constants.

Support SQL-92 syntax for IS TRUE/IS FALSE/IS NOT TRUE/IS NOT FALSE.

Allowed shorter strings for Boolean literals (for example, t, tr, tru).

Allowed SQL-92 delimited identifiers.

Implemented SQL-92 binary ...

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