sudo apt install mysql-client-core-5.7

Reading package lists... Done Building dependency tree        Reading state information... Done The following packages were automatically installed and are no longer required:   libnvidia-common-390 libwayland-client0:i386 libwayland-server0:i386 Use 'sudo apt autoremove' to remove them. The following NEW packages will be installed:   mysql-client-core-5.7 0 upgraded, 1 newly installed, 0 to remove and 4 not upgraded. Need to get 6,985 kB of archives. After this operation, 31.5 MB of additional disk space will be used. Ign:1 http://security.ubuntu.com/ubuntu bionic-security/main amd64 mysql-client-core-5.7 amd64
5.7.23-0ubuntu0.18.04.1 Err:1 http://us.archive.ubuntu.com/ubuntu bionic-security/main amd64 mysql-client-core-5.7 amd64
5.7.23-0ubuntu0.18.04.1   404  Not Found [IP: 91.189.88.161 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/m/mysql-5.7/mysql-client-core-5.7_5.7.23-0ubuntu0.18.04.1_amd64.deb 404  Not Found [IP: 91.189.88.161 80] E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

sudo apt update

sudo apt upgrade

# deb cdrom:[Ubuntu 18.04.1 LTS _Bionic Beaver_ - Release amd64 (20180725)]/ bionic main restricted

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://us.archive.ubuntu.com/ubuntu/ bionic main restricted
# deb-src http://us.archive.ubuntu.com/ubuntu/ bionic main restricted

## Major bug fix updates produced after the final release of the
## distribution.
# deb-src http://us.archive.ubuntu.com/ubuntu/ bionic-updates main restricted

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://us.archive.ubuntu.com/ubuntu/ bionic universe
# deb-src http://us.archive.ubuntu.com/ubuntu/ bionic universe
# deb-src http://us.archive.ubuntu.com/ubuntu/ bionic-updates universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://us.archive.ubuntu.com/ubuntu/ bionic multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ bionic multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ bionic-updates multiverse

## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
# deb-src http://us.archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse

## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu bionic partner
# deb-src http://archive.canonical.com/ubuntu bionic partner

deb http://security.ubuntu.com/ubuntu bionic-security main restricted
# deb-src http://security.ubuntu.com/ubuntu bionic-security main restricted
deb http://security.ubuntu.com/ubuntu bionic-security universe
# deb-src http://security.ubuntu.com/ubuntu bionic-security universe
deb http://security.ubuntu.com/ubuntu bionic-security multiverse
# deb-src http://security.ubuntu.com/ubuntu bionic-security multiverse
deb http://us.archive.ubuntu.com/ubuntu/ bionic-updates main restricted universe multiverse