Mysql prompts insufficient space in ubuntu

After the first prompt for this problem, I deleted the log file under var, but the same message is displayed after deletion. however, I had to unmount mysql, reinstall mysql, and restart mysql. dmysqlstart still prompts the same error mysqlERROR: Thepartitionwithvarlibmysqlistoofull! View the space usage: zhang @ zhang-Inspiron-N4050 :~ $ DfFilesystem1K-blocksUsedAvaila... mysqlubuntu

After the first prompt for this problem, I deleted the log file under var, but the same message is displayed after deletion.

However, I had to unmount mysql, reinstall mysql, and restart mysql. d mysql start, The same error mysqlERROR: The partition with/var/lib/mysql is too full!

The usage of the space is as follows:
Zhang @ zhang-Inspiron-N4050 :~ $ Df
Filesystem 1K-blocks Used Available Use % Mounted on
/Dev/sda8 56721716 8023228 45794120 15%/
None 4 0 4 0%/sys/fs/cgroup
Udev 965132 4 965128 1%/dev
Tmpfs 194948 1160 193788 1%/run
None 5120 0 5120 0%/run/lock
None 974740 80 974660 1%/run/shm
None 102400 36 102364 1%/run/user
Zhang @ zhang-Inspiron-N4050 :~ $
I hope that you will be grateful for the opportunity.

Why does the newly installed mysql prompt that the space is too full?