Scalar will return only one value.
(ie we can read or write only one data at the time)

When we want any aggreagate answer then we use execute 
scaler examples like avg,sum etc
this return one row and one column

It Returns Single Scalar value as a result

This method is used to execute commands that return single 
value rather than resultset.

when we want to retrieve data that has single value then we
can prefer to execute scalar.

execute scalar return a object type value, by defalut it 
will return first row of fst column value, mostly we used 
it with aggregate function like sum(),max(),min(),avg()....