GeezerVison

Summary

This PR introduces support for parsing MySQL ALTER TABLE statements with the following new options:

ALTER TABLE tbl_name
    [alter_option [, alter_option] ...]

  | ALTER {CHECK | CONSTRAINT} symbol [NOT] ENFORCED
  | ALTER [COLUMN] col_name {
        SET DEFAULT {literal | (expr)}
      | SET {VISIBLE | INVISIBLE}
      | DROP DEFAULT
    }
  | ALTER INDEX index_name {VISIBLE | INVISIBLE}

Changes

• Updated the parser to handle the new syntax for ALTER TABLE.
• Added support for parsing column visibility, default value modifications, and constraint enforcement.
• Enhanced the AlterExpression and related classes to accommodate the new options.

Testing

• Added unit tests to verify the parsing of the new ALTER TABLE syntax.
• Verified backward compatibility with existing ALTER TABLE statements.

Impact

This change enables the library to support advanced MySQL features, improving compatibility with modern MySQL versions.