What does mysql virtual column mean?

when building a table, how to understand the concept of virtual column? can you give me a column? thank you!

Mar.14,2021

In the

database, in order to speed up the search of data, we usually add an index. If you add a function to the selecte statement of mysql, then the index is invalid, so we can use a virtual column, which will specifically store the results after running the function.

http://www.techug.com/post/my.

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-64f5-1eaa3bb-1fc1.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1eaa3bb-1fc1.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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