----- Original Message ----- From: "Rob Kudyba" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Thursday, November 04, 2004 12:26 PM Subject: constructing a select and excluding duplicates
> I am trying to construct a SELECT statement on distinct email addresses. > Our DB has emails entered by various sources and there are duplicate > addresses based on the source. Using sample table names and sources here > is what I have: > > SELECT DISTINCT email_address > FROM 'email_table' > WHERE SOURCE = 'source 1' > > Simple enough, but I want to exclude email addresses that appear in > several other sources, i.e, something like in this pseudo sample: > > SELECT DISTINCT email_address > FROM [ENTIRE_TABLE_IN_DATABASE] > WHERE SOURCE = 'source 1' > AND EXCLUDE email_address IF SOURCE = [source 2, source 4, source 6] > Wouldn't it make a lot more sense to get rid of your duplicates FIRST? That is going to dramatically simplify your life for every other query you do. It's also going to reduce the size of your tables which should improve query performance and reduce hard disk usage. Rhino -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
