[thelist] DB "Limit" Command Question

Edward McCarroll Ed at ComSimplicity.com
Thu Apr 16 14:24:28 CDT 2009


> What if I run a 'select field1, field2, field3 from tableA' 
> that contains a 'limit output to 20 records" clause?

> Does it run through the whole table and then return 20 
> records?  Or does it stop executing at 20 records and return?

MS SQL Server offers "SELECT TOP <N> ..." which, when used without
an "ORDER BY" clause, returns N random rows.  (AFAIK, there's no
"limit output to 20 records" clause.)

I refuse to believe that any respectable DBMS would scan an entire
table if the goal was to find "N random rows".

But then again, those open-source folks have been known to take an
approach that differs from Micro$oft's. </troll>

"Some people really do prefer to curse the darkness."  (Ed McCarroll)
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Ed McCarroll                                     Ed at ComSimplicity.com
PO Box 654                                             (310) 904-3651
Culver City, CA 90232                           www.ComSimplicity.com
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