What is the difference between in and exists.
Ex: select * from emp where empno in(....) and
select * from emp where empno exists(....)
What is the difference between a Join and Union and Union
and UnionAll.
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Answer Posted / gopi muluka
IN:Returns true if the column matches to any value in a
subquery or a list.
Exists:Returns true if a subquery contains any row.
Generally EXISTS is faster than IN, because it stops
processing once it finds a row in resultset
Join : Returns only rows which are matching on Joining
Column
Union: Combines two or more resultsets with same number of
columns and displays it as a single resultset by
eliminating duplicate records
Union All: Combines two or more resultsets with same number
of columns,displays it as a single resultset including
duplicate records if any exists
| Is This Answer Correct ? | 16 Yes | 0 No |
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