Can we rewrite subqueries into simple select statements or with joins? Example?

Can we rewrite subqueries into simple select statements or
with joins? Example?

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Can we rewrite subqueries into simple select statements or with joins? Example?..

Answer / divya kalra

Subqueries can often be re-written to use a standard outer
join, resulting in faster performance. As we may know, an
outer join uses the plus sign (+) operator to tell the
database to return all non-matching rows with NULL values.
Hence we combine the outer join with a NULL test in the
WHERE clause to reproduce the result set without using a
sub-query.

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Can we rewrite subqueries into simple select statements or with joins? Example?..

Answer / syed sajjad

Yes we can write using Common Table Expression (CTE). A Common Table Expression (CTE) is an expression that can be thought of as a temporary result set which is defined within the execution of a single SQL statement. A CTE is similar to a derived table in that it is not stored as an object and lasts only for the duration of the query.

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