创建数据库：

const std::string createImMessageIndex =

 "CREATE UNIQUE INDEX IF NOT EXISTS sessionid_idx ON immessage(msgId DESC,sessionId);";

删除条数：

const std::string DeleteMessageBySId

+ = "delete from immessage2 where msgId = ? and sessionid = ?";

更新：

const std::string UpdateMessageFileUrlBySId

= "update immessage set orifileurl = ? where msgId = ? and sessionid =?";

全清：

const std::string ClearAllChatMessage

= "delete from immessage";

获取全部信息：

const std::string CalculateMessageChartSize

 = "select * from immessage";