Support for Databricks GENERATED ALWAYS AS (expr) is incomplete

[crash-g]

The following code will throw sqlglot.errors.ParseError: Expecting ), even though it is a valid CREATE statement.

import sqlglot

sql = """
CREATE TABLE IF NOT EXISTS db.table (
  a  TIMESTAMP,
  b  BOOLEAN GENERATED ALWAYS AS (a IS NOT NULL)
)
USING DELTA
"""

sqlglot.parse_one(sql, read="databricks")

Tested with latest version (23.12.2) and with main.

GENERATED ALWAYS AS documentation: https://docs.databricks.com/en/sql/language-manual/sql-ref-syntax-ddl-create-table-using.html