in a select statement, is the order of elements in the where clause the determining factor on what records are chosen first, second etc?
No. The optimizer examines the query to determine the most efficient way to execute the query. You can get information about how the optimizer views a SELECT statement by issuing it with the word EXPLAIN prepended:
EXPLAIN select fname from maintable where status=1 and dob > '2001-03-10';
for instance...
select fname from maintable where status=1 and dob > '2001-03-10';
does that mean that the records will first be checked for status creating a pool of records with status=1 to then check for dob out of that pool or if one of the fields is an index will it automatically use the index first or does it use some other ordering methodology?
TIA
Larry
-- Paul DuBois, MySQL Documentation Team Madison, Wisconsin, USA MySQL AB, www.mysql.com
MySQL Users Conference: April 14-16, 2004 http://www.mysql.com/uc2004/
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