In general, you need to delay the answer from the server for 25 seconds for example …
I tried the function Sleep (), but is there anything suitable?
Answer 1, Authority 100%
In your case, dig it in the direction of comet .
If lazy or not the opportunity to understand, I advise you to put a delay between queries of seconds 20 and return only new data.
And what did Sleep fit? You can make a sample number of count records from the table, and check the specified time interval if Count has changed / increased data. To do this, you can use the same SLEEP