Query to compare signup date to FIRST purchase date

[Louise99]

I have two tables. One has my customer name and ID with the date of their sign-up. The other has the customer ID with the dates of orders. I need to compare the databases to find out the what the time is between the sign-up and the FIRST order. One confusing factor: there may be more than one signup date because the "new signup" can expire. There aren't very many of those but there are some. Should I move the duplicates to a new table. Any advice?

Thanks!

 

[lespaul]

how do you determine which records have "expired"? Do they get a new customer number if they sign up again?

Something like:

SELECT C.CustomerID, C.CustomerName, C.DateOfSignup, O.DateOfFirstOrder FROM Customer
INNER JOIN (SELECT CustomerID, MIN(OrderDate) As DateOfFirstOrder FROM Orders GROUP BY CustomerID) O ON C.CustomerID = O.CustomerID
WHERE C.ExpiredSignUp = False

Leslie

Anything worth doing is a lot more difficult than it's worth - Unknown Induhvidual

Essential reading for anyone working with databases:
The Fundamentals of Relational Database Design
Understanding SQL Joi