Differentiate between Hash join, Sort Merge join and Nested Loop join

1.	Differentiate between Hash join, Sort Merge join and Nested Loop join in DBMS.
Answer» Hash-join: A hash join is a form of physical join method that is used to join two tables internally. The fact that the join is an internal join technique implies that we can't see it. The query optimizer does the join selection automatically. Sort Merge Join: In the case of SORTED relations, the Sort Merge Join is the quickest join. This join, like the nested loop join, is an internal join. We can't observe or IMPLEMENT the algorithm; all we can do is direct the engine to utilize it. The merge and sort PHASES of this method are used for combining and sorting tasks, respectively. Nested Loop join: In a nested loop join, the driving table (MAIN) retrieves rows by index range scan, and the driving table's result set is nested with the probing of the other (SECONDARY) table via the index scan method.

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