I have the following My Guitar Shop exercise in my SQL II course and am stumped with the part about getting the results in ascending order through the cursor. Any advice is appreciated.
Here are my instructions:
"Write a script that utilizes a cursor to print the lastname of each customer in the customers table along with the number of orders that customer has placed.
Print the results to the screen in ascending order by number of order placed.
Include a total at the end that shows the total number of orders placed."
Here's my code:
USE MyGuitarShop;
/* Write a script that utilizes a cursor to print the lastname of each customer in the customers table
along with the number of orders that customer has placed.
Print the results to the screen in ascending order by number of order placed.
Include a total at the end that shows the total number of orders placed.*/
DECLARE #CustID int;
DECLARE #CustLastName varchar(60);
DECLARE #TotalOrders int;
SET #TotalOrders = 0;
DECLARE Orders_Cursor CURSOR
FOR
SELECT CustomerID, LastName
FROM Customers
OPEN Orders_Cursor;
FETCH NEXT FROM Orders_Cursor INTO #CustID, #CustLastName
DECLARE #OrderCount int;
WHILE ##FETCH_STATUS <> -1
BEGIN
PRINT #CustLastName + ': ' + CONVERT(varchar,#OrderCount);
SELECT #OrderCount = COUNT(OrderID)
FROM Orders
WHERE CustomerID = #CustID
ORDER BY COUNT(OrderID) ASC;
SET #TotalOrders = #TotalOrders + #OrderCount
FETCH NEXT FROM Orders_Cursor INTO #CustID, #CustLastName;
END;
PRINT 'Total number of orders placed: ' + CONVERT(varchar, #TotalOrders);
CLOSE Orders_Cursor;
DEALLOCATE Orders_Cursor;
Everything works accept the ascending order and I have spent hours and hours and cannot figure this out. Any tips to lead me in the right direction is appreciated.
If I understand your question correctly, you just need list all the customers with the order count.
You can create one cursor directly based on below SQL statement:
SELECT c.CustomerID, c.LastName, COUNT(o.orderid) as orderCount FROM
customers c LEFT JOIN orders o
ON c.LastName = o.LastName GROUP BY c.LastName ORDER BY orderCount;
In your implementation, in the sub-sql, you query the order count for a specified customer and order by , the order by is useless for only one customer.
Related
I have a list of teams in one table and list of cases in another table. I have to allocate a unique random case number to each one of the members in the team. What is the best way to generate unique random case number for each team member. I have read about NewID() and CRYPT_GEN_RANDOM(4) functions. I tried using them but not getting unique number for each team member. Can some one please help me. Thanks for your time. I am using SQL 2008.
I have a 'Teams' table which has team members, their ids(TM1,TM2 etc.) and their names.
I have another 'Cases' table which has ID numbers like 1,2,3,4 etc. I want to allocate random case to each team member. The desired output should be as below.
Team member Random_case_allocated
TM1 3
TM2 5
TM3 7
TM4 2
TM5 8
TM6 6
I have tried
SELECT TOP 1 id FROM cases
ORDER BY CRYPT_GEN_RANDOM(4)
It is giving the same id for all team members. I want a different case id for each team member. Can someone please help. Thank you.
The TOP(1) ORDER BY NEWID() will not work the way you are trying to get it to work here. The TOP is telling the query engine you are only interested on the first record of the result set. You need to have the NEWID() evaluate for each record. You can force this inside of a window function, such as ROW_NUMBER(). This could optimized I would imagine, however, it was what I could come up with from the top of my head. Please note, this is not nearly a truly random algorithm.
UPDATED With Previous Case Exclusions
DECLARE #User TABLE(UserId INT)
DECLARE #Case TABLE(CaseID INT)
DECLARE #UserCase TABLE (UserID INT, CaseID INT, DateAssigned DATETIME)
DECLARE #CaseCount INT =10
DECLARE #SaveCaseID INT = #CaseCount
DECLARE #UserCount INT = 100
DECLARE #NumberOfUserAllocatedAtStart INT= 85
WHILE(#CaseCount > 0)BEGIN
INSERT #Case VALUES(#CaseCount)
SET #CaseCount = #CaseCount-1
END
DECLARE #RandomCaseID INT
WHILE(#UserCount > 0)BEGIN
INSERT #User VALUES(#UserCount)
SET #UserCount = #UserCount-1
IF(#NumberOfUserAllocatedAtStart > 0 )BEGIN
SET #RandomCaseID = (ABS(CHECKSUM(NewId())) % (#SaveCaseID))+1
INSERT #UserCase SELECT #UserCount,#RandomCaseID,DATEADD(MONTH,-3,GETDATE())
SET #RandomCaseID = (ABS(CHECKSUM(NewId())) % (#SaveCaseID))+1
INSERT #UserCase SELECT #UserCount,#RandomCaseID,DATEADD(MONTH,-5,GETDATE())
SET #RandomCaseID = (ABS(CHECKSUM(NewId())) % (#SaveCaseID))+1
INSERT #UserCase SELECT #UserCount,#RandomCaseID,DATEADD(MONTH,-2,GETDATE())
SET #NumberOfUserAllocatedAtStart=#NumberOfUserAllocatedAtStart-1
END
END
;WITH RowNumberWithNewID AS
(
SELECT
U.UserID, C.CaseID, UserCase_CaseID = UC.CaseID,
RowNumber = ROW_NUMBER() OVER (PARTITION BY U.UserID ORDER BY NEWID())
FROM
#User U
INNER JOIN #Case C ON 1=1
LEFT OUTER JOIN #UserCase UC ON UC.UserID=U.UserID AND UC.CaseID=C.CaseID AND UC.DateAssigned > DATEADD(MONTH, -4, UC.DateAssigned)
WHERE
UC.CaseID IS NULL OR UC.CaseID <> C.CaseID
)
SELECT
UserID,
CaseID,
PreviousCases = STUFF((SELECT ', '+CONVERT(NVARCHAR(10), UC.CaseID) FROM #UserCase UC WHERE UC.UserID=RN.UserID FOR XML PATH('')),1,1,'')
FROM RowNumberWithNewID RN
WHERE
RN.RowNumber=1
Is it possible to have the result set of a stored procedure limited to 25 results, but also return the total number of results (not limited)? This stored procedure is used in a search page on a web application, so we have paged results (displaying 25 results per page), but need the ##rowcount to display 'Your results returned ___' results.
I've tried the obvious approaches like
SELECT COUNT(*)
FROM [derived table containing the search query]
but due to data structure, the number of rows in participating tables, the COUNT(*) is taking longer than the query itself.
I apologize in advance for the formatting sticklers out there, still very new to this!
You could try to use WITH common_table_expression.
WITH ResultSet AS
(
select CustomerID,CompanyName, ROW_NUMBER() over (Order by CompanyName asc) as RowNumber from Customers
)
select CustomerID,CompanyName,(Select Max(RowNumber) From ResultSet) AS TotalCount from ResultSet
where RowNumber > 0 and RowNumber < 25
In this case CompanyName would be sorting field and you can calculate the max RowNumber then apply pagination on it.
Another option is
declare #pageIndex int = 1
declare #pageCount int = 25
SELECT CustomerID, CompanyName,COUNT(*) OVER () as TotalCount
FROM Customers
ORDER BY CompanyName
OFFSET ( #pageIndex-1 ) * #pageCount ROWS
FETCH NEXT #pageCount ROWS ONLY
Demo
If you query the Count not from the derived table but from the original tables, and only get only the count that should be faster than from a derived table. You can then store that in an output parameter.
Other then that I don't see another way to do this.
so why not do:
declare #numrows int;
SELECT #numrows = Count(*) FROM sys.databases;
PRINT #numrows; -- or assign to output param
The query:
SELECT TOP 1000 t.columns
FROM dbo.teams as t
RIGHT JOIN fnParseString('Nugget,Tulsa',',') ps ON t.team_name LIKE '%'+ps.string+'%' OR t.nickname LIKE '%'+ps.string+'%'
This does return the results I want, but but the ordering isn't useful.
I may add more columns to the search.
How do I rank the rows based on accuracy and number of matched terms? I know it only needs to match one of the terms to be selected, is there a way to then count the number of terms that match the columns.
I see Need help with SQL for ranking search results but will the subselect work for an arbitrary number of search tokens
If you are open to some dynamic SQL
Declare #SearchFor varchar(max) ='Daily,Production,default' -- Any comma delim string
Declare #SearchFrom varchar(150) ='OD' -- table or even a join statemtn
Declare #SearchExpr varchar(150) ='[OD-Title]' -- Any field or even expression
Declare #ReturnCols varchar(150) ='[OD-Nr],[OD-Title]' -- Any field(s) even with alias
Set #SearchFor = 'Sign(CharIndex('''+Replace(Replace(Replace(#SearchFor,' , ',','),', ',''),',',''','+#SearchExpr+'))+Sign(CharIndex(''')+''','+#SearchExpr+'))'
Declare #SQL nvarchar(Max) = 'Select * from (Select Distinct'+#ReturnCols+',Hits='+#SearchFor+' From '+#SearchFrom + ') A Where Hits>0 Order by Hits Desc'
Exec(#SQL)
Returns
OD-Nr OD-Title Hits
3 Daily Production Summary 2
6 Default Settings 1
Non-dynamic option, for contrast. You'd have to add to the order by and the join as you add more columns to check.
SELECT TOP 1000 t.columns
FROM dbo.teams as t
RIGHT JOIN fnParseString('Nugget,Tulsa',',') ps
ON t.team_name LIKE '%'+ps.string+'%'
OR t.nickname LIKE '%'+ps.string+'%'
order by
case when t.team_name LIKE '%'+ps.string+'%' then 1 else 0 +
case when t.nickname LIKE '%'+ps.string+'%' then 1 else 0
desc
I have a sql server table named Student like below:
I wish to select the students with the highest score from each class, which shall produce the output like this:
Due to some constraint, I can't be sure how many unique class names would exist in the table. My stored procedure is :
create procedure selectBestStudent
as
begin
select Name, max(TestScore)
from [TestDB1].[dbo].[StudentTest]
group by Name
end
But the result is wrong. Any idea?
You can use ROW_NUMBER with a PARTITION BY:
SELECT Name, Class, TestScore
FROM (
SELECT Name, Class, TestScore,
ROW_NUMBER() OVER (PARTITION BY Class
ORDER BY TestScore DESC) AS rn
FROM StudentTest) AS t
WHERE t.rn = 1
ROW_NUMBER enumerates records within each Class partition: the ORDER BY clause guarantees that the record having the greatest TestScore value is assigned a value equal to 1.
Note: To handle ties you can use RANK in place of ROW_NUMBER. This way you can get all students that share the same maximum TestScore for the same Class.
You can also achieve this goal with NOT EXISTS()
SELECT * FROM Student s
WHERE NOT EXISTS(select 1 FROM Student t
where t.class = s.class
and t.testScore > s.testScore)
This will select only those rows that doesn't have a row with a higher value on testScore
I think you will have a problem with the Group By and the MAX() when there are multiple people with the same score in a class.
I solved it with a fetch if you don't know yet what this is, you can look here. It's easier than it looks at the beginning!
I know that might be a horrible way to do it but its's easy to understand and it worked! :D
USE [TestDB]
GO
DECLARE #class char(10), #testscore int;
DECLARE #result Table
(
Name char(10),
Class char(10),
TestScore int
);
-- Get Classes and their Maxima
DECLARE TestScore_cursor CURSOR FOR SELECT [class], MAX([testscore]) FROM [student] GROUP BY [class];
OPEN TestScore_cursor;
-- Perform the first fetch.
FETCH NEXT FROM TestScore_cursor INTO #class, #testscore;
-- Check ##FETCH_STATUS to see if there are any more rows to fetch.
WHILE ##FETCH_STATUS = 0
BEGIN
-- Search Students by Class and Score and add them to tempTable #result
INSERT INTO #result SELECT [name], [class], [testscore] From [student] where [testScore] = #testscore AND [class] = #class;
FETCH NEXT FROM TestScore_cursor INTO #class, #testscore;
END
-- Show the Result
SELECT * FROM #result;
CLOSE TestScore_cursor;
DEALLOCATE TestScore_cursor;
GO
I was looking at different ways of writing a stored procedure to return a "page" of data. This was for use with the ASP ObjectDataSource, but it could be considered a more general problem.
The requirement is to return a subset of the data based on the usual paging parameters; startPageIndex and maximumRows, but also a sortBy parameter to allow the data to be sorted. Also there are some parameters passed in to filter the data on various conditions.
One common way to do this seems to be something like this:
[Method 1]
;WITH stuff AS (
SELECT
CASE
WHEN #SortBy = 'Name' THEN ROW_NUMBER() OVER (ORDER BY Name)
WHEN #SortBy = 'Name DESC' THEN ROW_NUMBER() OVER (ORDER BY Name DESC)
WHEN #SortBy = ...
ELSE ROW_NUMBER() OVER (ORDER BY whatever)
END AS Row,
.,
.,
.,
FROM Table1
INNER JOIN Table2 ...
LEFT JOIN Table3 ...
WHERE ... (lots of things to check)
)
SELECT *
FROM stuff
WHERE (Row > #startRowIndex)
AND (Row <= #startRowIndex + #maximumRows OR #maximumRows <= 0)
ORDER BY Row
One problem with this is that it doesn't give the total count and generally we need another stored procedure for that. This second stored procedure has to replicate the parameter list and the complex WHERE clause. Not nice.
One solution is to append an extra column to the final select list, (SELECT COUNT(*) FROM stuff) AS TotalRows. This gives us the total but repeats it for every row in the result set, which is not ideal.
[Method 2]
An interesting alternative is given here (https://web.archive.org/web/20211020111700/https://www.4guysfromrolla.com/articles/032206-1.aspx) using dynamic SQL. He reckons that the performance is better because the CASE statement in the first solution drags things down. Fair enough, and this solution makes it easy to get the totalRows and slap it into an output parameter. But I hate coding dynamic SQL. All that 'bit of SQL ' + STR(#parm1) +' bit more SQL' gubbins.
[Method 3]
The only way I can find to get what I want, without repeating code which would have to be synchronized, and keeping things reasonably readable is to go back to the "old way" of using a table variable:
DECLARE #stuff TABLE (Row INT, ...)
INSERT INTO #stuff
SELECT
CASE
WHEN #SortBy = 'Name' THEN ROW_NUMBER() OVER (ORDER BY Name)
WHEN #SortBy = 'Name DESC' THEN ROW_NUMBER() OVER (ORDER BY Name DESC)
WHEN #SortBy = ...
ELSE ROW_NUMBER() OVER (ORDER BY whatever)
END AS Row,
.,
.,
.,
FROM Table1
INNER JOIN Table2 ...
LEFT JOIN Table3 ...
WHERE ... (lots of things to check)
SELECT *
FROM stuff
WHERE (Row > #startRowIndex)
AND (Row <= #startRowIndex + #maximumRows OR #maximumRows <= 0)
ORDER BY Row
(Or a similar method using an IDENTITY column on the table variable).
Here I can just add a SELECT COUNT on the table variable to get the totalRows and put it into an output parameter.
I did some tests and with a fairly simple version of the query (no sortBy and no filter), method 1 seems to come up on top (almost twice as quick as the other 2). Then I decided to test probably I needed the complexity and I needed the SQL to be in stored procedures. With this I get method 1 taking nearly twice as long as the other 2 methods. Which seems strange.
Is there any good reason why I shouldn't spurn CTEs and stick with method 3?
UPDATE - 15 March 2012
I tried adapting Method 1 to dump the page from the CTE into a temporary table so that I could extract the TotalRows and then select just the relevant columns for the resultset. This seemed to add significantly to the time (more than I expected). I should add that I'm running this on a laptop with SQL Server Express 2008 (all that I have available) but still the comparison should be valid.
I looked again at the dynamic SQL method. It turns out I wasn't really doing it properly (just concatenating strings together). I set it up as in the documentation for sp_executesql (with a parameter description string and parameter list) and it's much more readable. Also this method runs fastest in my environment. Why that should be still baffles me, but I guess the answer is hinted at in Hogan's comment.
I would most likely split the #SortBy argument into two, #SortColumn and #SortDirection, and use them like this:
…
ROW_NUMBER() OVER (
ORDER BY CASE #SortColumn
WHEN 'Name' THEN Name
WHEN 'OtherName' THEN OtherName
…
END *
CASE #SortDirection
WHEN 'DESC' THEN -1
ELSE 1
END
) AS Row
…
And this is how the TotalRows column could be defined (in the main select):
…
COUNT(*) OVER () AS TotalRows
…
I would definitely want to do a combination of a temp table and NTILE for this sort of approach.
The temp table will allow you to do your complicated series of conditions just once. Because you're only storing the pieces you care about, it also means that when you start doing selects against it further in the procedure, it should have a smaller overall memory usage than if you ran the condition multiple times.
I like NTILE() for this better than ROW_NUMBER() because it's doing the work you're trying to accomplish for you, rather than having additional where conditions to worry about.
The example below is one based off a similar query I'm using as part of a research query; I have an ID I can use that I know will be unique in the results. Using an ID that was an identity column would also be appropriate here, though.
--DECLARES here would be stored procedure parameters
declare #pagesize int, #sortby varchar(25), #page int = 1;
--Create temp with all relevant columns; ID here could be an identity PK to help with paging query below
create table #temp (id int not null primary key clustered, status varchar(50), lastname varchar(100), startdate datetime);
--Insert into #temp based off of your complex conditions, but with no attempt at paging
insert into #temp
(id, status, lastname, startdate)
select id, status, lastname, startdate
from Table1 ...etc.
where ...complicated conditions
SET #pagesize = 50;
SET #page = 5;--OR CAST(#startRowIndex/#pagesize as int)+1
SET #sortby = 'name';
--Only use the id and count to use NTILE
;with paging(id, pagenum, totalrows) as
(
select id,
NTILE((SELECT COUNT(*) cnt FROM #temp)/#pagesize) OVER(ORDER BY CASE WHEN #sortby = 'NAME' THEN lastname ELSE convert(varchar(10), startdate, 112) END),
cnt
FROM #temp
cross apply (SELECT COUNT(*) cnt FROM #temp) total
)
--Use the id to join back to main select
SELECT *
FROM paging
JOIN #temp ON paging.id = #temp.id
WHERE paging.pagenum = #page
--Don't need the drop in the procedure, included here for rerunnability
drop table #temp;
I generally prefer temp tables over table variables in this scenario, largely so that there are definite statistics on the result set you have. (Search for temp table vs table variable and you'll find plenty of examples as to why)
Dynamic SQL would be most useful for handling the sorting method. Using my example, you could do the main query in dynamic SQL and only pull the sort method you want to pull into the OVER().
The example above also does the total in each row of the return set, which as you mentioned was not ideal. You could, instead, have a #totalrows output variable in your procedure and pull it as well as the result set. That would save you the CROSS APPLY that I'm doing above in the paging CTE.
I would create one procedure to stage, sort, and paginate (using NTILE()) a staging table; and a second procedure to retrieve by page. This way you don't have to run the entire main query for each page.
This example queries AdventureWorks.HumanResources.Employee:
--------------------------------------------------------------------------
create procedure dbo.EmployeesByMartialStatus
#MaritalStatus nchar(1)
, #sort varchar(20)
as
-- Init staging table
if exists(
select 1 from sys.objects o
inner join sys.schemas s on s.schema_id=o.schema_id
and s.name='Staging'
and o.name='EmployeesByMartialStatus'
where type='U'
)
drop table Staging.EmployeesByMartialStatus;
-- Populate staging table with sort value
with s as (
select *
, sr=ROW_NUMBER()over(order by case #sort
when 'NationalIDNumber' then NationalIDNumber
when 'ManagerID' then ManagerID
-- plus any other sort conditions
else EmployeeID end)
from AdventureWorks.HumanResources.Employee
where MaritalStatus=#MaritalStatus
)
select *
into #temp
from s;
-- And now pages
declare #RowCount int; select #rowCount=COUNT(*) from #temp;
declare #PageCount int=ceiling(#rowCount/20); --assuming 20 lines/page
select *
, Page=NTILE(#PageCount)over(order by sr)
into Staging.EmployeesByMartialStatus
from #temp;
go
--------------------------------------------------------------------------
-- procedure to retrieve selected pages
create procedure EmployeesByMartialStatus_GetPage
#page int
as
declare #MaxPage int;
select #MaxPage=MAX(Page) from Staging.EmployeesByMartialStatus;
set #page=case when #page not between 1 and #MaxPage then 1 else #page end;
select EmployeeID,NationalIDNumber,ContactID,LoginID,ManagerID
, Title,BirthDate,MaritalStatus,Gender,HireDate,SalariedFlag,VacationHours,SickLeaveHours
, CurrentFlag,rowguid,ModifiedDate
from Staging.EmployeesByMartialStatus
where Page=#page
GO
--------------------------------------------------------------------------
-- Usage
-- Load staging
exec dbo.EmployeesByMartialStatus 'M','NationalIDNumber';
-- Get pages 1 through n
exec dbo.EmployeesByMartialStatus_GetPage 1;
exec dbo.EmployeesByMartialStatus_GetPage 2;
-- ...etc (this would actually be a foreach loop, but that detail is omitted for brevity)
GO
I use this method of using EXEC():
-- SP parameters:
-- #query: Your query as an input parameter
-- #maximumRows: As number of rows per page
-- #startPageIndex: As number of page to filter
-- #sortBy: As a field name or field names with supporting DESC keyword
DECLARE #query nvarchar(max) = 'SELECT * FROM sys.Objects',
#maximumRows int = 8,
#startPageIndex int = 3,
#sortBy as nvarchar(100) = 'name Desc'
SET #query = ';WITH CTE AS (' + #query + ')' +
'SELECT *, (dt.pagingRowNo - 1) / ' + CAST(#maximumRows as nvarchar(10)) + ' + 1 As pagingPageNo' +
', pagingCountRow / ' + CAST(#maximumRows as nvarchar(10)) + ' As pagingCountPage ' +
', (dt.pagingRowNo - 1) % ' + CAST(#maximumRows as nvarchar(10)) + ' + 1 As pagingRowInPage ' +
'FROM ( SELECT *, ROW_NUMBER() OVER (ORDER BY ' + #sortBy + ') As pagingRowNo, COUNT(*) OVER () AS pagingCountRow ' +
'FROM CTE) dt ' +
'WHERE (dt.pagingRowNo - 1) / ' + CAST(#maximumRows as nvarchar(10)) + ' + 1 = ' + CAST(#startPageIndex as nvarchar(10))
EXEC(#query)
At result-set after query result columns:
Note:
I add some extra columns that you can remove them:
pagingRowNo : The row number
pagingCountRow : The total number of rows
pagingPageNo : The current page number
pagingCountPage : The total number of pages
pagingRowInPage : The row number that started with 1 in this page