Where we are going to use "Derived Tables" (In which scenario they are mandatory) ?


Can you please let me know in which scenarios derived tables are mandatory to use ?

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Guy Hengel [angelIII / a3]Billing EngineerCommented:
from syntax point of view, they are not "mandatory". you could always solve the problem with temp tables.
from performance point of view, they are very useful and powerful.
Steve HoggITCommented:
Agreed, I prefer the use of derived but not required.

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A "derived table" is a syntax for creating a temporary name (alias) for a table expression within the scope of a single query. It is used mainly to simplify the SQL by using the name instead of repeating a complex expression.

The only time I can think of when derived tables are essential is for recursive queries (recursive CTEs). A recursive CTE (Common Table Expression) is a special kind of derived table.
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Microsoft SQL Server 2008

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