How to count down the countdown to Synchronize for multiple clients

the application scenario is that the landlord plays the cards sequentially and each player plays the cards for 30 seconds. You can reconnect with the seniors to instruct the server. Thank you

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Feb.28,2021

the client can display the countdown, but it is only a fake for the user to see. The real timing should be done on the server side. There is only one room in the same room, and each player takes turns to use it.

MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1beb7bb-31a9d.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1beb7bb-31a9d.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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