default-libmysqlclient-dev binary package in Ubuntu Focal amd64

 MySQL is a fast, stable and true multi-user, multi-threaded SQL database
 server. SQL (Structured Query Language) is the most popular database query
 language in the world. The main goals of MySQL are speed, robustness and
 ease of use.
 .
 This package depends on the default implementation of the client development
 libraries and header files (API and ABI defined by MySQL). Depending on the
 default defined through this metapackage, the underlying implementation may be
 provided by either MySQL or MariaDB. Build-Depend on this package and then
 link using -lmysqlclient. You will end up with a binary that depends on either
 libmysqlclient.so.X or libmariadbclient.so.X depending on the current default.
 dpkg-shlibdeps should correctly generate a dependency on libmysqlclientX or
 libmariadbclientX as appropriate.

Source package