My Sales.Customer table includes the following columns:
CustomerID (integer)
FirstName (nvarchar(50))
LastName (nvarchar(50))
My Sales.SalesOrder table includes the following columns:
SalesOrderNumber (integer)
OrderDate (date)
CustomerID (integer)
Amount (money)
Some customers have placed multiple orders over a period of years. I've written the following query to retrieve the last date on which each customer placed an order:
SELECT c.CustomerID, c.FirstName, c.LastName,
-- correlated subquery goes here
AS LastOrderDate
FROM Sales.Customer AS c;
Why does my subquery not complete my actual query? Am I missing something or should it be something different?
(SELECT MAX(o.OrderDate)
FROM Sales.SalesOrder AS o
WHERE o.CustomerID = c.CustomerID)
I considered whether I might be over-complicating my solution so maybe this should work instead?
(SELECT MAX(c.OrderDate)
FROM Sales.Customer AS c)
You should be able to rewrite it as a CTE like this.
;WITH LastOrderDate AS
(
SELECT CustomerID,MAX(OrderDate) AS LastOrderDate
FROM Sales.SalesOrder
GROUP BY CustomerID
)
SELECT c.CustomerID, c.FirstName, c.LastName, LastOrderDate
AS LastOrderDate
FROM Sales.Customer AS c
LEFT JOIN LastOrderDate l
ON c.CustomerID = l.CustomerID;
Related
I have 3 tables in SQL Server:
Sales (customerId)
Customer (customerId, personId)
Person (personId, firstName, lastName)
and I need to return the top 10 customers.
I used this query:
SELECT TOP 10
CustomerID, COUNT(CustomerID)
FROM
Sales
GROUP BY
(CustomerID)
ORDER BY
COUNT(CustomerID) DESC
The query currently returns only the customerId and count, but I also need to return the firstName and lastName of these customers from the Person table.
I know I need to reach the firstName and lastName by correlating between Sales.customerId and Customer.customerId, and from Customer.personId to get the Person.personId.
My question is whether I need to use an inner join or union, and how to use either of them to get the firstName and lastName of these customers
Union is mostly used for disjoint sets. To achieve your target, u can go with inner-join.
If you want to use joins, then here is the query which works similarly to your requirement.
SELECT TOP 10 S.CustomerID, P.FirstName,P.LastName, count(*)
FROM Sales S
INNER JOIN Customer C on S.CustomerId=C.CustomerId
INNER JOIN Person P on C.PersonId = P.PersonId
GROUP BY (S.CustomerID, P.FirstName,P.LastName)
ORDER BY count(*) DESC
You need use inner join like this :
SELECT TOP 10 S.CustomerID
, P.FirstName
, P.LastName
, COUNT (1) AS CountOfCustomer -- this is equal count(*)
FROM Sales S
INNER JOIN Customer C ON S.CustomerId = C.CustomerId
INNER JOIN Person P ON C.PersonId = P.PersonId
GROUP BY S.CustomerID, P.FirstName, P.LastName
ORDER BY 4 DESC; -- this is equal order by count(*)
select D.[Date], E.emp_name, E.emp_jde, count(C.[agent_no]) calls, count(S.[EMPJDENUM]) sales
from
(select cast([start_date] as date) dte, [agent_no]
from call_table
where [skill_name] like '%5700 sales l%'
and [Agent_Time] != '0'
) C
full outer join
(select [AC#DTE_dt], [EMPJDENUM]
from sales_table
where [ICGCD2] in ('LAWN', 'HORT')
and [CHANNEL]= 'INQ'
and [ITMQTY]>3
) S on c.dte=s.[AC#DTE_dt]
right join
(select [Date]
from Date_table
) D on c.dte=d.[Date] or s.[AC#DTE_dt]=d.[Date]
right join
(select [emp_name], [emp_jde], [agent_no]
from Employee_table
) E on C.[agent_no]=E.agent_no and S.[EMPJDENUM]=E.emp_jde
group by D.[Date], E.emp_name, E.emp_jde
Date Tables -
Note: Not all dates will have both calls and sales.
Additional Tables -
What needs to be accomplished -
1) Join and Aggregate calls and sales by Employee by joining the calls table (on agent_no) and sales (on JDE) table
2) Since not all dates will include both calls and sales - use the date dimension table to ensure all dates are represented
The desired result would look like this -
The query I wrote executes - it takes so long I just end up canceling the query.
Any help would be appreciated.
Without seeing the query plan, it is a little tricky, but here are a couple of suggestions that might improve the performance:
remove the leading wildcard in where [skill_name] like '5700 sales l%'
put the group by into the subqueries
I have an example here that implements both of those. (Note that I did some reformatting just to try to understand what your query was doing.)
select D.[Date], E.emp_name, E.emp_jde, C.Calls, S.Sales
from Date_table As D
Left Join (
select cast([start_date] as date) As CallDate, [agent_no], Count(*) As Calls
from call_table
where [skill_name] like '5700 sales l%'
and [Agent_Time] != '0'
Group By Cast([start_date] As date), [agent_no]) As C On D.[Date] = C.CallDate
Left Join (
select [AC#DTE_dt] As SaleDate, [EMPJDENUM], Count(*) As Sales
from sales_table
where [ICGCD2] in ('LAWN', 'HORT')
and [CHANNEL]= 'INQ'
and [ITMQTY]>3
Group By [AC#DTE_dt], [EMPJDENUM]) As S on D.[Date] = s.SaleDate
right join Employee_table As E
on C.[agent_no]=E.agent_no
and S.[EMPJDENUM]=E.emp_jde;
Edit
In order to get a row for each possible combination of date and employee, you will need a cross join of the date table and the employee table.
select D.[Date], E.emp_name, E.emp_jde, C.Calls, S.Sales
from Date_table As D,
Employee_table as E
Left Join (
select cast([start_date] as date) As CallDate, [agent_no], Count(*) As Calls
from call_table
where [skill_name] like '5700 sales l%'
and [Agent_Time] != '0'
Group By Cast([start_date] As date), [agent_no]) As C
On D.[Date] = C.CallDate
And E.agent_no = C.agent_no
Left Join (
select [AC#DTE_dt] As SaleDate, [EMPJDENUM], Count(*) As Sales
from sales_table
where [ICGCD2] in ('LAWN', 'HORT')
and [CHANNEL]= 'INQ'
and [ITMQTY]>3
Group By [AC#DTE_dt], [EMPJDENUM]) As S
on D.[Date] = s.SaleDate
and E.emp_jde = S.[EMPJDENUM];
I have 2 tables.
Contacts
ContactID pk
EmailAddress
FirstName
LastName
Address
Orders
OrderID pk
ContactID fk
I want to get the number or orders for each email address in Contacts like below
select
Contacts.EmailAddress,
count(distinct Orders.OrderID) AS NumOrders
from
Contacts inner join Orders on Contacts.ContactID = Orders.ContactID
group by
Contacts.EmailAddress
Problem is, I also want the first name, last name, address. But I can't group by those because each email address in Contacts could have a different first name, lastname or address associated with it.
ie:
myname#email.com, Fred, Jackson, 123 Main St
myname#email.com, Bob, Smith, 456 Spruce St.
How can I change my query so that I can get the first name, last name and address for the most recent entry made in Contacts for that email address?
Thanks in advance!
My first thought would be to use windowed functions.
SELECT EmailAddress,
FirstName,
Lastname,
[Address],
EmailOrderCount
FROM (SELECT c.EmailAddress,
c.FirstName,
c.LastName,
c.[Address],
COUNT(o.OrderID) OVER (PARTITION BY c.EmailAddress) EmailOrderCount,
ROW_NUMBER() OVER (PARTITION BY c.EmailAddress ORDER BY c.ContactID DESC) Rn
FROM Contacts c
JOIN Orders o ON c.ContactID = o.ContactID
) t
WHERE Rn = 1
Demo
another way would be to use CROSS APPLY to append the top 1 contact record to the summary rows.
SELECT c.EmailAddress,
COUNT(o.OrderID) NumOrders,
ca.FirstName,
ca.LastName,
ca.[Address]
FROM Contacts c
INNER JOIN Orders ON c.ContactId = o.ContactID
CROSS APPLY (
SELECT TOP 1
FirstName,
Lastname,
[Address]
FROM Contacts c2
WHERE c2.EmailAddress = c.EmailAddress
ORDER BY c2.ContactID DESC) ca
GROUP BY c.EmailAddress,
ca.FirstName,
ca.LastName,
ca.[Address]
Try this:
select
Contacts.Name,
Contacts.FirstName,
Contacts.LastName
Contacts.EmailAddress,
count(distinct Orders.OrderID) AS NumOrders
from
(
select max(ContactID) as ContactID,
EmailAddress
from Contacts
group by EmailAddress
) MinContactForEachEMailAddress
inner join
Contacts
on MinContactForEachEMailAddress.ContactID = Contacts.ContactID
inner join
Orders
on Contacts.ContactID = Orders.ContactID
group by
Contacts.EmailAddress
Another way to get what you want is using a CTE and taking the "maximum" row by using ROW_NUMBER.
;WITH CTE AS (
SELECT C.ContactId, C.Name, C.FirstName, C.LastName, C.EmailAddress,
ROW_NUMBER() OVER (PARTITION BY EmailAddress ORDER BY ContactId DESC) RowNo
FROM Contact C
)
SELECT CTE.*, COUNT(o.OrderID) OVER (PARTITION BY CTE.EmailAddress) Cnt
FROM CTE
JOIN Orders O on CTE.ContactID = O.ContactID
-- select the "maximum" row
WHERE CTE.RowNo = 1
An easy way to do this is to make your original query a subquery and select from it. I'm making a slight change, because it's a better practice to group by your primary key than your email address. (Is it a safe bet that each contact has just one email address, and that the basic intent is to group by person?) If so, try this:
SELECT DISTINCT c.EmailAddress, c.FirstName, c.LastName, c.Address, sub.NumOrders
FROM
(
select
Contacts.ContactID
count(distinct Orders.OrderID) AS NumOrders
from
Contacts inner join Orders on Contacts.ContactID = Orders.ContactID
group by
Contacts.ContactID
) sub
JOIN Contacts c
ON sub.ContactID = c.ContactID
If you really need to group by email address instead, then change the above subquery to your original query and change c.EmailAddress to sub.EmailAddress. Of course you may order the SELECT fields however best suits you.
Edit follows:
The ContactID must be a sequence number and you can continually put the same person in the table. So if you add the DISTINCT keyword in the outer query I believe that will give you what you need.
I was trying to write a query for the SQL Server sample DB Northwind. The question was: "Show the most recent five orders that were purchased by a customer who has spent more than $25,000 with Northwind."
In my query the Alias name - "Amount" is not being recognized. My query is as follows:
select top(5) a.customerid, sum(b.unitprice*b.quantity) as "Amount", max(c.orderdate) as Orderdate
from customers a join orders c
on a.customerid = c.customerid
join [order details] b
on c.orderid = b.orderid
group by a.customerid
--having Amount > 25000 --throws error
having sum(b.unitprice*b.quantity) > 25000 --works, but I don't think that this is a good solution
order by Orderdate desc
Pls let me know what I am doing wrong here, as I am a newbie in writing T Sql. Also can this query and my logic be treated as production level query?
TIA,
You must use the aggregate in the query you have. This all has to do with the order in which a SELECT statement is executed. The syntax of the SELECT statement is as follows:
SELECT
FROM
WHERE
GROUP BY
HAVING
ORDER BY
The order in which a SELECT statement is executed is as follows. Since the SELECT clause isn't executed until after the HAVING clause, you can't use the alias like you can in the ORDER BY clause.
FROM
WHERE
GROUP BY
HAVING
SELECT
ORDER BY
Reference Article: http://www.bennadel.com/blog/70-sql-query-order-of-operations.htm
This is a known limitation in SQL Server, at least, but no idea if it's a bug, intentional or even part of the standard. But the thing is, neither the WHERE or HAVING clauses accept an alias as part of their conditions, you must use only columns from the original source tables, which means that for filtering by calculated expressions, you must copy-paste the very same thing in both the SELECT and WHERE parts.
A workaround for avoiding this duplication can be to use a subquery or cte and apply the filter on the outer query, when the alias is just an "input" table:
WITH TopOrders AS (
select a.customerid, sum(b.unitprice*b.quantity) as "Amount", max(c.orderdate) as Orderdate
from customers a join orders c
on a.customerid = c.customerid
join [order details] b
on c.orderid = b.orderid
group by a.customerid
--no filter here
order by Orderdate desc
)
SELECT TOP(5) * FROM TopOrders WHERE Amount > 25000 ;
Interesting enough, the ORDER BY clause does accepts aliases directly.
You must use Where b.unitprice*b.quantity > 25000 instead of having Amount > 25000.
Having used for aggregate conditions. Your business determine your query condition. If you need to calculate sum of prices that have above value than 25000, must be use Where b.unitprice*b.quantity > 25000 and if you need to show customer that have total price above than 25000 must be use having Amount > 25000 in your query.
select top(5) a.customerid, sum(b.unitprice*b.quantity) as Amount, max(c.orderdate) as Orderdate
from customers a
JOIN orders c ON a.customerid = c.customerid
join [order details] b ON c.orderid = b.orderid
group by a.customerid
having sum(b.unitprice*b.quantity) > 25000 --works, but I don't think that this is a good solution
Order by Amount
I don't have that schema at hand, so table' and column' names might go a little astray, but the principle is the same:
select top (5) ord2.*
from (
select top (1) ord.CustomerId
from dbo.Orders ord
inner join dbo.[Order Details] od on od.OrderId = ord.OrderId
group by ord.CustomerId
having sum(od.unitPrice * od.Quantity) > $25000
) sq
inner join dbo.Orders ord2 on ord2.CustomerId = sq.CustomerId
order by ord2.OrderDate desc;
The Having Clause will works with aggregate function like SUM,MAX,AVG..
You may try like this
SELECT TOP 5 customerid,SUM(Amount)Amount , MAX(Orderdate) Orderdate
FROM
(
SELECT A.customerid, (B.unitprice * B.quantity) As "Amount", C.orderdate As Orderdate
FROM customers A JOIN orders C ON A.customerid = C.customerid
JOIN [order details] B ON C.orderid = B.orderid
) Tmp
GROUP BY customerid
HAVING SUM(Amount) > 25000
ORDER BY Orderdate DESC
The question is little ambiguos.
Show the most recent five orders that were purchased by a customer who
has spent more than $25,000 with Northwind.
Is it asking to show the 5 recent orders by all the customers who have spent more than $25,000 in all of their transactions (which can be more than 5).
The following query shows all the customers who spent $25000 in all of their transactions (not just the recent 5).
In one of the Subquery BigSpenders it gets all the Customers who spent more than $25000.
Another Subquery calculates the total amount for each order.
Then it gets rank of all the orders by OrderDate and OrderID.
Then it filters it by Top 5 orders for each customer.
--
SELECT *
FROM (SELECT C.customerid,
C.orderdate,
C.orderid,
B3.amount,
Row_number()
OVER(
partition BY C.customerid
ORDER BY C.orderdate DESC, C.orderid DESC) Rank
FROM orders C
JOIN
--Get Amount Spend Per Order
(SELECT b2.orderid,
Sum(b2.unitprice * b2.quantity) AS Amount
FROM [order details] b2
GROUP BY b2.orderid) B3
ON C.orderid = B3.orderid
JOIN
--Get Customers who spent more than 25000
(SELECT c.customerid
FROM orders c
JOIN [order details] b
ON c.orderid = b.orderid
GROUP BY c.customerid
HAVING Sum(b.unitprice * b.quantity) > 25000) BigSpenders
ON C.customerid = BigSpenders.customerid) X
WHERE X.rank <= 5
The objective is below the list of tables.
Tables:
Table: Job
JobID
CustomerID
Value
Year
Table: Customer
CustomerID
CustName
Table: Invoice
SaleAmount
CustomerID
The Objective
Part 1: (easy) I need to select all invoice records and sort by Customer (To place nice w/ Crystal Reports)
Select * from Invoice as A inner join Customer as B on A.CustomerID = B.CustomerID
Part 2: (hard) Now, we need to add two fields:
JobID associated with that customer's job that has the Maximum Value (from 2008)
Value associated with that job
Pseudo Code
Select * from
Invoice as A
inner join Customer as B on A.CustomerID = B.CustomerID
inner join
(select JobID, Value from Jobs where Job:JobID has the highest value out of all of THIS customer's jobs from 2008)
General Thoughts
This is fairly easy to do If I am only dealing with one specific customer:
select max(JobId), max(Value) as MaxJobID from Jobs where Value = (select max(Value) from Jobs where CustomerID = #SpecificCustID and Year = '2008') and CustomerID = SpecificCustID and CustomerID = '2008'
This subquery determines the max Value for this customer in 2008, and then its a matter of choosing a single job (can't have dupes) out of potential multiple jobs from 2008 for that customer that have the same value.
The Difficulty
What happens when we don't have a specific customer ID to compare against? If my goal is to select ALL invoice records and sort by customer, then this subquery needs access to which customer it is currently dealing with. I suppose this can "sort of" be done through the ON clause of the JOIN, but that doesn't really seem to work because the sub-sub query has no access to that.
I'm clearly over my head. Any thoughts?
How about using a CTE. Obviously, I can't test, but here is the idea. You need to replace col1, col2, ..., coln with the stuff you want to select.
Inv( col1, col2, ... coln)
AS
(
SELECT col1, col2, ... coln,
ROW_NUMBER() OVER (PARTITION BY A.CustomerID
ORDER BY A.Value DESC) AS [RowNumber]
FROM Invoice A INNER JOIN Customer B ON A.CustomerID = B.CustomerID
WHERE A.CustomerID = #CustomerID
AND A.Year = #Year
)
SELECT * FROM Inv WHERE RowNumber = 1
If you don't have a CustomerID, this will return the top value for each customer (that will hurt on performance tho).
The row_number() function can give you what you need:
Select A.*, B.*, C.JobID, C.Value
from
Invoice as A
inner join Customer as B on A.CustomerID = B.CustomerID
inner join (
select JobID, Value, CustomerID,
ROW_NUMBER() OVER (PARTITION BY CustomerID ORDER BY Value DESC) AS Ordinal
from Jobs
WHERE Year = 2008
) AS C ON (A.CustomerID = C.customerID AND C.Ordinal = 1)
The ROW_NUMBER() function in this query will order by value in descending order and the PARTITION BY clause will do this separately for each different value of CustomerID. This means that the highest Value for each customer will always be 1, so we can join to that value.
The over function is an awesome, but often neglected function. You can use it in a subquery to pull back your valid jobs, like so:
select
a.*
from
invoice a
inner join customer b on
a.customerid = b.customerid
inner join (select customerid, max(jobid) as jobid, maxVal from
(select customerid,
jobid,
value,
max(value) over (partition by customerid) as maxVal
from jobs
where Year = '2008') s
where s.value = s.maxVal
group by customerid, maxVal) c on
b.customerid = c.customerid
and a.jobid = c.jobid
Essentially, that first inner query looks like this:
select
customerid,
jobid,
value,
max(value) over (partition by customerid) as maxVal
from jobs
where Year = '2008'
You'll see that this pulls back all of the jobs, but with that additional column which lets you know what the maximum value is for each customer. With the next subquery, we filter out any rows that have value and maxVal equal. Additionally, it finds the max JobID based on customerid and maxVal, because we need to pull back one and only one JobID (as per the requirements).
Now, you have a complete listing of CustomerID and JobID that meet the conditions of having the highest JobID that contains the maximum Value for that CustomerID in a given year. All that's left is to join it to Invoice and Customer, and you're good to go.
Just to be complete with the non row_number solution for those < MSSQL 2005. Personanly, I find it easier to follow myslef...but that could be biased considering how much time I spend in MSSQL 2000 vs 2005+.
SELECT *
FROM Invoice as A
INNER JOIN Customer as B ON
A.CustomerID = B.CustomerID
INNER JOIN (
SELECT
CustomerId,
--MAX in case dupe Values.
==If UC on CustomerId, Value (or CustomerId, Year, Value) then not needed
MAX(JobId) as JobId
FROM Jobs
JOIN (
SELECT
CustomerId,
MAX(Value) as MaxValue
FROM Jobs
WHERE Year = 2008
GROUP BY
CustomerId
) as MaxValue ON
Jobs.CustomerId = MaxValue.CustomerId
AND Jobs.Value = MaxValue.MaxValue
WHERE Year = 2008
GROUP BY
CustomerId
) as C ON
B.CustomerID = C.CustomerID