Following on from G H I've added the user and host parameters incase you need to do this on a remote server
#!/bin/bash
# mycollate.sh <database> <user> <password> [<host> <charset> <collation>]
# changes MySQL/MariaDB charset and collation for one database - all tables and
# all columns in all tables
DB="$1"
USER="$2"
PW="$3"
HOST="$4"
CHARSET="$5"
COLL="$6"
[ -n "$DB" ] || exit 1
[ -n "$USER" ] || exit 1
[ -n "$PW" ] || exit 1
[ -n "$HOST" ] || HOST="localhost"
[ -n "$CHARSET" ] || CHARSET="utf8mb4"
[ -n "$COLL" ] || COLL="utf8mb4_general_ci"
PW="--password=""$PW"
HOST="--host=""$HOST"
USER="--user=""$USER"
echo $DB
echo "ALTER DATABASE $DB CHARACTER SET $CHARSET COLLATE $COLL;" | mysql "$HOST" "$USER" "$PW"
echo "USE $DB; SHOW TABLES;" | mysql "$HOST" "$USER" "$PW" | (
while read TABLE; do
echo $DB.$TABLE
echo "ALTER TABLE $TABLE CONVERT TO CHARACTER SET $CHARSET COLLATE $COLL;" | mysql "$HOST" "$USER" "$PW" $DB
done
)
PW="pleaseEmptyMeNow"