/**
     * SEQUENCE means a separate sequence object will be used. Platforms that do
     * not have native sequence support may emulate it. Full portability is currently
     * not guaranteed.
     */
    const GENERATOR_TYPE_SEQUENCE = 2;

    /**
     * IDENTITY means an identity column is used for id generation. The database
     * will fill in the id column on insertion. Platforms that do not support
     * native identity columns may emulate them. Full portability is currently
     * not guaranteed.
     */
    const GENERATOR_TYPE_IDENTITY = 4;