Mutating Error In Database Trigger

Mutating error is one of the common error which one encounters while working with triggers which can involve operation of a particular table. Mutating error in database triggers is the error encountered by oracle while working or implicitly executing a database trigger. Mutating error, generally this error occurs when a row-level trigger accesses the same table on which it is based the trigger is being executed. This gives Mutating Error in database triggers. The mutating error is database triggers is on variouls DML statement executed on a table on which a database triggers exists. 

A user sees the error (ORA-04091)- Table is mutating mainly on any DML statement is executed on a table.
The mutating error (ORA-04091) mostly occurs  during the DML insert, updates and deletes present in the trigger statement.