What database should be used to store the content of books?

prepare to develop book reading class app, backend to choose which database can better store book content. In the past, relational databases were used. Experienced people can guide them

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Mar.03,2021

not to mention what kind of database, books, such as resources, I will save to the hard disk in the form of a file, instead of directly saving it in the database, saving it in the database, just a physical address of the file.

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-64f5-1e4487f-44ace.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1e4487f-44ace.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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