CREATE TABLE ChatMessageRecord ( 
    AutoID      INTEGER           PRIMARY KEY AUTOINCREMENT
                                  NOT NULL,
    SpeakerID   VARCHAR( 0, 20 )  NOT NULL,
    AudienceID  VARCHAR( 0, 20 )  NOT NULL,
    IsGroupChat BOOLEAN           NOT NULL,
    Content     BLOB              NOT NULL,
    OccureTime  DATETIME          NOT NULL 
);
CREATE INDEX idx_ChatMessageRecord ON ChatMessageRecord ( 
    SpeakerID,
    AudienceID,
    OccureTime DESC 
);
CREATE INDEX idx2_ChatMessageRecord ON ChatMessageRecord ( 
    AudienceID,
    IsGroupChat,
    OccureTime 
);
