execution plan analysis

Hello,

Please refer to the below output.My point of discussion is- I created a table emp_data with empid as integer (10) and empname as char(10)  and I created index on empname then select empid,empname from emp_data where empname='dave' used index on empname in the plan hoowever then I created another table emp_data1 with empid as number(6) and empname as varchar(10) when I created similar index on this table even then it used the table access full however when I created composite index on empid and empname it used that index and when I made this composite index invisible this time it