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AskSQLTeam
Ask SQLTeam Question
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 Posted - 2001-09-03 : 09:16:02
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| Allen Myers writes "This might be a simple question as my SQL knowledge is minimal. I'm trying to figure out how to get a query to return only the records that do not exist in a particular query the original is compared against, with a twist... read on.For instance, I have a table called "Users" and a table called "Orders". I'd like to generate a query that shows me only users that have NO associated orders yet.I know I can use the NOT IN clause in some manner like:SELECT Users.UserIDFROM UsersWHERE Users.UserID NOT IN (SELECT Orders.UserID FROM Orders);(I'm using Access with JetSQL so bear with me if my syntax is off a bit.)Now, for the twist. Let's say the "Orders" table is actually a query. And the "Orders" query takes about 5-7 seconds to generate itself once. From my understanding, the "Orders" query will be ran once for each record compared to in the "Users" table. ACK! If I have about 300 users, that could easily add up to 30 minutes to run the query!!!Isn't there a simpler/faster way to just compare against the "Orders" query once so I only have to wait 5-7 seconds for it to run once!?!?Thanks in advance." |
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