How to run multiple SQL queries whose values change? - sql

Question

Let's say I have a database of Amazon customers who made purchases in the last year. It is pretty detailed and has columns like name, age, zip code, income level, favorite color, food, music, etc. Now, let's say I run a query such that I return all Amazon customers who bought Book X.
SELECT NAME, AGE, ZIPCODE, INCOME, FAVECOLOR, FAVEFOOD, FAVEMUSIC
FROM [Amazon].[dbo].[Customers]
WHERE BOOK = "X"
This query will return a bunch of customers who bought Book X. Now, I want to iterate through each of those results (iterate through each customer) and create a query based on each customer's individual age, zipcode, and income.
So if the first result is Bob, age 32, lives in zipcode 90210, makes $45,000 annually, create a query to find all others like Bob who share the same age, zipcode, and income. If the second result is Mary, age 41, lives in zipcode 10004, makes $55,000 annually, create a query to find all others like Mary who share the same age, zipcode, and income.
How do I iterate through customers who bought Book X and run multiple queries whose values (age, zipcode, income) are changing? In terms of viewing the results, it'd be great if I could see Bob, followed by all customers who are like Bob, then Mary, and all customers who are like Mary.
Is this even possible in SQL? I know how to do this in C# (for/next loops with if/then statements inside) but am new to SQL, and the data is in SQL.
I use SQL Server 2008.

Answer 1

If i understood your requirement correctly then a nested quesry should do the job. SOmething like this:
SELECT distinct NAME, AGE, ZIPCODE, INCOME, FAVECOLOR, FAVEFOOD, FAVEMUSIC
FROM [Amazon].[dbo].[Customers] a, (SELECT NAME, AGE, ZIPCODE, INCOME, FAVECOLOR, FAVEFOOD, FAVEMUSIC
FROM [Amazon].[dbo].[Customers]
WHERE BOOK = "X" and name = 'Bob') b
WHERE BOOK = "X" and a.age=b.age and a.zipcode= b.zipcode and a.income=b.income
EDIT: A generic query will be [This will have list of all users]:
SELECT distinct NAME, AGE, ZIPCODE, INCOME, FAVECOLOR, FAVEFOOD, FAVEMUSIC
FROM [Amazon].[dbo].[Customers] a, (SELECT distinct NAME, AGE, ZIPCODE, INCOME, FAVECOLOR, FAVEFOOD, FAVEMUSIC
FROM [Amazon].[dbo].[Customers]
WHERE BOOK = "X" ) b
WHERE a.BOOK = b.book and a.age=b.age and a.zipcode= b.zipcode and a.income=b.income
order by name

Answer 2

Something like this can do it in one query:
;WITH cteSource as
(
SELECT NAME, AGE, ZIPCODE, INCOME, FAVECOLOR, FAVEFOOD, FAVEMUSIC
FROM [Amazon].[dbo].[Customers]
WHERE BOOK = "X"
)
SELECT sr.NAME AS SrcName, cu.NAME AS LikeName
FROM [Amazon].[dbo].[Customers] AS cu
JOIN cteSource As sr
ON cu.AGE = sr.AGE
And cu.ZIPCODE = sr.ZIPCODE
And cu.INCOME = sr.INCOME

Answer 3

Something like this will let you chase related customers to an arbitrary, e.g. 5 here, degree of separation. By constructing the JOINs correctly you can do things like match income within a range, ... .
with Book as (
select Id, Name, Age, ZIPCode, Income -- ...
from Amazon.dbo.Customers
where Book = 'X' ),
RelatedCustomers as (
select C.Id, C.Name, C.Age, C.ZIPCode, C.Income, 1 as Depth -- ...
from Amazon.dbo.Customers as C inner join
Book as B on B.Id <> C.Id and Abs( B.Income - C.Income ) < 2000 -- and ...
union all
select C.Id, C.Name, C.Age, C.ZIPCode, C.Income, RC.Depth + 1-- ...
from Amazon.dbo.Customers as C inner join
RelatedCustomers as RC on RC.Id <> C.Id and Abs( RC.Income - C.Income ) < 2000 -- and ...
where Depth < 5 )
select *
from RelatedCustomers

Answer 4

I think you need two separate queries. First one to bring back the customers, once a customer such as Bob is selected a second query is performed based on Bob's attributes.
A simple example would be a forms application that has two grids. The first displays a list of the users. When you select one of the users the second grid is populated with the results of the second query.
The second query would be something like:
SELECT NAME, AGE, ZIPCODE, INCOME, FAVECOLOR, FAVEFOOD, FAVEMUSIC
FROM [Amazon].[dbo].[Customers]
WHERE Age = #BobsAge AND ZipCode = #BobsZipCode AND Income = #BobsIncome
It sounds like you want a simple self-join:
SELECT
MatchingCustomers.NAME,
MatchingCustomers.AGE,
MatchingCustomers.ZIPCODE,
MatchingCustomers.INCOME,
MatchingCustomers.FAVECOLOR,
MatchingCustomers.FAVEFOOD,
MatchingCustomers.FAVEMUSIC
FROM
[Amazon].[dbo].[Customers] SourceCustomer
LEFT JOIN [Amazon].[dbo].[Customers] MatchingCustomers
ON SourceCustomer.Age = MatchingCustomer.Age
AND SourceCustomer.ZipCode = MatchingCustomer.ZipCode
AND SourceCustomer.Income = MatchingCustomer.Income
WHERE
SourceCustomer.Book = 'X'
If you want to see the all source customers and all of their matches in a single result set you can remove the where clause and select data SourceCustomer also:
SELECT
SourceCustomer.Name SourceName,
SourceCustomer.Age SourceAge
SourceCustomer.ZipCode SourceZipCode,
SourceCustomer.Income SourceIncome,
MatchingCustomers.NAME,
MatchingCustomers.AGE,
MatchingCustomers.ZIPCODE,
MatchingCustomers.INCOME,
MatchingCustomers.FAVECOLOR,
MatchingCustomers.FAVEFOOD,
MatchingCustomers.FAVEMUSIC
FROM
[Amazon].[dbo].[Customers] SourceCustomer
LEFT JOIN [Amazon].[dbo].[Customers] MatchingCustomers
ON SourceCustomer.Age = MatchingCustomer.Age
AND SourceCustomer.ZipCode = MatchingCustomer.ZipCode
AND SourceCustomer.Income = MatchingCustomer.Income
WHERE
SourceCustomer.Book = 'X'