TSQLDiaper = class(TSQLRecord)
  private
    fSerialNumber: RawUTF8;
    fModel: TSQLDiaperModel;
    fBaby: TSQLBaby;
  published
    property SerialNumber: RawUTF8
     index 30
      read fSerialNumber write fSerialNumber
     stored AS_UNIQUE;
    property Model: TSQLDiaperModel read fModel write fModel;
    property Baby: TSQLBaby read fBaby write fBaby;
end;

字段后面加  stored AS_UNIQUE;
就会创建索引