How to resolve Freeradius Error: rlm_sql_mysql: MYSQL Error: No Fields

deleting the space from sql: Update section did the tricks.

Example :

%{sql: delete from radacct  WHERE UserName='%{User-Name}'  and  CallingStationId='%{Calling-Station-Id}';}

Edit to :

%{sql:delete from radacct  WHERE UserName='%{User-Name}'  and  CallingStationId='%{Calling-Station-Id}';}

refer : http://freeradius.1045715.n5.nabble.com/Deleting-stale-session-automatically-with-unlang-td3340701.html