Why can a "group by" or "order by" clause be expensive to process? what is the difference between a where and having clause?

Answer and Explanation:

Group by clause bunches every one of the information coming back from the question in the predetermined gatherings.  

Order by clause will arrange the information either in rising  or in dropping order depending on the section data or column data.  

It is certainly a lengthy from execution perspective.  

Envision that the quantity of columns returned by the question are millions and gathering and arranging information from this parcel takes bigger execution time.  

The procedure is a lot of equivalent to on the off chance that you are approached to arrange the precisely coordinating names in a populace measurements, it requires colossal measure of handling time to make sense of the precisely coordinating names and after that arranging them as needs be.

The distinction between where and having clause:

'Where' and having clause in SQL are utilized to indicate separating conditions.  

There is a little contrast between these two clause and is given as under:  

WHERE clause is utilized while getting data (lines or rows) from the table, and the information which clears the condition will only be considered into  the result set.

HAVING clause is later utilized to channel a data summary or gathered data.  

On the off chance that the two clauses show up in SQL question, where clause will execute at first and afterward having clause is executed on the groups that returns the group clause.