SQL Puzzler 3/8/2019

This is an actual requirement that I got from a customer today, so I'm challenging you to see if you can figure out how to code it in SQL. 

Give it a careful though before you read my answer. 

Leave a comment if you have something that will work better, or is more elegant.

So, we start with this:

declare  @Order table(RowID int identity,Invoice varchar(20), CustomerID varchar(20), CustomerEmail varchar(100), DocAmount numeric(19,2) )
insert into @Order (Invoice, CustomerID, CustomerEmail, DocAmount) values ('INV00100','001','Joe@Acompany.com',100)
insert into @Order (Invoice, CustomerID, CustomerEmail, DocAmount) values ('INV00101','002','Sam@Bcompany.com',110)
insert into @Order (Invoice, CustomerID, CustomerEmail, DocAmount) values ('INV00102','003','Bob@Ccompany.com',120)
insert into @Order (Invoice, CustomerID, CustomerEmail, DocAmount) values ('INV00103','004','Tom@Dcompany.com',130)
insert into @Order (Invoice, CustomerID, CustomerEmail, DocAmount) values ('INV00104','005','Flo@Fcompany.com',140)
insert into @Order (Invoice, CustomerID, CustomerEmail, DocAmount) values ('INV00105','006','Tim@Gcompany.com',150)
insert into @Order (Invoice, CustomerID, CustomerEmail, DocAmount) values ('INV00106','006','Tim2@Gcompany.com',160)
insert into @Order (Invoice, CustomerID, CustomerEmail, DocAmount) values ('INV00107','008','Sal@Hcompany.com',170)
insert into @Order (Invoice, CustomerID, CustomerEmail, DocAmount) values ('INV00108','008','Sal2@Hcompany.com',180)
insert into @Order (Invoice, CustomerID, CustomerEmail, DocAmount) values ('INV00109','008','Sal3@Hcompany.com',190)
 
select * from @Order

This will give us an ORDER table that looks like the below. 10 lines, from 8 companies. The requirement is this:

Use the order table to update the email address field in the customer table. If the same customer has two email address, the newest one should be the main email address, the second oldest one should be the CC, and discard any older email addresses. 

The final result should look like the second screen shot. 

How would you code that?

 

 

Related Articles

... and you 'll find more on the SQL (General) Menu

Here's my answer. Excited to see what you came up with!

declare @Customer table (CustomerID varchar(20), Email varchar(100), EmailCC varchar(100) )
 
insert into @Customer (CustomerID, Email, EmailCC)
select
        t.CustomerID,
        max(t.email) as Email,
        max(t.EmailCC) as EmailCC
    from (
        SELECT customerid,
                case when rowid = 1 then CustomerEmail else '' end as Email,
                case when rowid = 2 then CustomerEmail else '' end as EmailCC
            FROM (
                select o.CustomerID, o.CustomerEmail,
                        ROW_NUMBER() over (partition by CustomerID order by rowid) as RowID
                    from @Order o
                ) T
        ) t
    group by CustomerID
Select * from @Customer

 

 

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