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SQL: Select the first of each set

Timothy Chen Allen
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Joined: Mar 16, 2003
Posts: 161
I have a table like this. It's a ledger. Each entry is associated with an invoice number, and there is a transaction type and a description. The table is sorted by invoice and transaction type:

I need to extract a listing of invoices and their descriptions-- however, the client is only interested in the very first description of each invoice, so this isn't about doing a concatonation.
If I do this right, the list above will produce:

I'm currently doing this with a cursor (I'm in SQL Server 2000), but there are 700,000 records, so this is taking far too long. How can I do this without a cursor (I run through the list, recording the inveoice number, and write out the record to another table when the invoice number changes), or at least more quickly? Thanks in advance.
[ November 20, 2003: Message edited by: Tim Allen ]

Timothy Chen Allen
Learn Spanish in Washington, DC
Jeanne Boyarsky
author & internet detective
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Joined: May 26, 2003
Posts: 30580
    
154

Tim,
That's a good idea to store a table with the results. Take a look at triggers. You can set one up so that when the base table changes, your auxillary one is updated too (if neccessary.)


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subject: SQL: Select the first of each set