Dynamic SELECT statement, generate columns based on present and future values - sql

Question

Currently building a SELECT statement in SQL Server 2008 but would like to make this SELECT statement dynamic, so the columns can be defined based on values in a table. I heard about pivot table and cursors, but seems kind of hard to understand at my current level, here is the code;
DECLARE #date DATE = null
IF #date is null
set # date = GETDATE() as DATE
SELECT
Name,
value1,
value2,
value3,
value4
FROM ref_Table a
FULL OUTER JOIN (
SELECT
PK_ID ID,
sum(case when FK_ContainerType_ID = 1 then 1 else null) Box,
sum(case when FK_ContainerType_ID = 2 then 1 else null) Pallet,
sum(case when FK_ContainerType_ID = 3 then 1 else null) Bag,
sum(case when FK_ContainerType_ID = 4 then 1 else null) Drum
from
Packages
WHERE
#date between PackageStart AND PackageEnd
group by PK_ID ) b on a.Name = b.ID
where
Group = 0
The following works great for me , but PK_Type_ID and the name of the column(PackageNameX,..) are hard coded, I need to be dynamic and it can build itself based on present or futures values in the Package table.
Any help or guidance on the right direction would be greatly appreciated...,
As requested
ref_Table (PK_ID, Name)
1, John
2, Mary
3, Albert
4, Jane
Packages (PK_ID, FK_ref_Table_ID, FK_ContainerType_ID, PackageStartDate, PackageEndDate)
1 , 1, 4, 1JAN2014, 30JAN2014
2 , 2, 3, 1JAN2014, 30JAN2014
3 , 3, 2, 1JAN2014, 30JAN2014
4 , 4, 1, 1JAN2014, 30JAN2014
ContainerType (PK_ID, Type)
1, Box
2, Pallet
3, Bag
4, Drum
and the result should look like this;
Name Box Pallet Bag Drum
---------------------------------------
John 1
Mary 1
Albert 1
Jane 1
The following code like I said works great, the issue is the Container table is going to grow and I need to replicated the same report without hard coding the columns.

Answer 1

What you need to build is called a dynamic pivot. There are plenty of good references on Stack if you search out that term.
Here is a solution to your scenario:
IF OBJECT_ID('tempdb..##ref_Table') IS NOT NULL
DROP TABLE ##ref_Table
IF OBJECT_ID('tempdb..##Packages') IS NOT NULL
DROP TABLE ##Packages
IF OBJECT_ID('tempdb..##ContainerType') IS NOT NULL
DROP TABLE ##ContainerType
SET NOCOUNT ON
CREATE TABLE ##ref_Table (PK_ID INT, NAME NVARCHAR(50))
CREATE TABLE ##Packages (PK_ID INT, FK_ref_Table_ID INT, FK_ContainerType_ID INT, PackageStartDate DATE, PackageEndDate DATE)
CREATE TABLE ##ContainerType (PK_ID INT, [Type] NVARCHAR(50))
INSERT INTO ##ref_Table (PK_ID,NAME)
SELECT 1,'John' UNION
SELECT 2,'Mary' UNION
SELECT 3,'Albert' UNION
SELECT 4,'Jane'
INSERT INTO ##Packages (PK_ID, FK_ref_Table_ID, FK_ContainerType_ID, PackageStartDate, PackageEndDate)
SELECT 1,1,4,'2014-01-01','2014-01-30' UNION
SELECT 2,2,3,'2014-01-01','2014-01-30' UNION
SELECT 3,3,2,'2014-01-01','2014-01-30' UNION
SELECT 4,4,1,'2014-01-01','2014-01-30'
INSERT INTO ##ContainerType (PK_ID, [Type])
SELECT 1,'Box' UNION
SELECT 2,'Pallet' UNION
SELECT 3,'Bag' UNION
SELECT 4,'Drum'
DECLARE #DATE DATE, #PARAMDEF NVARCHAR(MAX), #COLS NVARCHAR(MAX), #SQL NVARCHAR(MAX)
SET #DATE = '2014-01-15'
SET #COLS = STUFF((SELECT DISTINCT ',' + QUOTENAME(T.[Type])
FROM ##ContainerType T
FOR XML PATH, TYPE).value('.', 'NVARCHAR(MAX)'),1,1,'')
SET #SQL = 'SELECT [Name], ' + #COLS + '
FROM (SELECT [Name], [Type], 1 AS Value
FROM ##ref_Table R
JOIN ##Packages P ON R.PK_ID = P.FK_ref_Table_ID
JOIN ##ContainerType T ON P.FK_ContainerType_ID = T.PK_ID
WHERE #DATE BETWEEN P.PackageStartDate AND P.PackageEndDate) X
PIVOT (COUNT(Value) FOR [Type] IN (' + #COLS + ')) P
'
PRINT #COLS
PRINT #SQL
SET #PARAMDEF = '#DATE DATE'
EXEC SP_EXECUTESQL #SQL, #PARAMDEF, #DATE=#DATE
Output:
Name Bag Box Drum Pallet
Albert 0 0 0 1
Jane 0 1 0 0
John 0 0 1 0
Mary 1 0 0 0

Answer 2

Static Query:
SELECT [Name],[Box],[Pallet],[Bag],[Drum] FROM
(
SELECT *
FROM
(
SELECT rf.Name,cnt.[Type], pk.PK_ID AS PKID, rf.PK_ID AS RFID
FROM ref_Table rf INNER JOIN Packages pk ON rf.PK_ID = pk.FK_ref_Table_ID
INNER JOIN ContanerType cnt ON cnt.PK_ID = pk.FK_ContainerType_ID
) AS SourceTable
PIVOT
(
COUNT(PKID )
FOR [Type]
IN ( [Box],[Pallet],[Bag],[Drum])
) AS PivotTable
) AS Main
ORDER BY RFID
Dynamic Query:
DECLARE #columnList nvarchar (MAX)
DECLARE #pivotsql nvarchar (MAX)
SELECT #columnList = STUFF(
(
SELECT ',' + '[' + [Type] + ']'
FROM ContanerType
FOR XML PATH( '')
)
,1, 1,'' )
SET #pivotsql =
N'SELECT [Name],' + #columnList + ' FROM
(
SELECT *
FROM
(
SELECT rf.Name,cnt.[Type], pk.PK_ID AS PKID, rf.PK_ID AS RFID
FROM ref_Table rf INNER JOIN Packages pk ON rf.PK_ID = pk.FK_ref_Table_ID
INNER JOIN ContanerType cnt ON cnt.PK_ID = pk.FK_ContainerType_ID
) AS SourceTable
PIVOT
(
COUNT(PKID )
FOR [Type]
IN ( ' + #columnList + ')
) AS PivotTable
) AS Main
ORDER BY RFID;'
EXEC sp_executesql #pivotsql
Following my tutorial below will help you to understand the PIVOT functionality:
We write sql queries in order to get different result sets like full, partial, calculated, grouped, sorted etc from the database tables. However sometimes we have requirements that we have to rotate our tables. Sounds confusing?
Let's keep it simple and consider the following two screen grabs.
SQL Table:
Expected Results:
Wow, that's look like a lot of work! That is a combination of tricky sql, temporary tables, loops, aggregation......, blah blah blah
Don't worry let's keep it simple, stupid(KISS).
MS SQL Server 2005 and above has a function called PIVOT. It s very simple to use and powerful. With the help of this function we will be able to rotate sql tables and result sets.
Simple steps to make it happen:
Identify all the columns those will be part of the desired result set.
Find the column on which we will apply aggregation(sum,ave,max,min etc)
Identify the column which values will be the column header.
Specify the column values mentioned in step3 with comma separated and surrounded by square brackets.
So, if we now follow above four steps and extract information from the above sales table, it will be as below:
Year, Month, SalesAmount
SalesAmount
Month
[Jan],[Feb] ,[Mar] .... etc
We are nearly there if all the above steps made sense to you so far.
Now we have all the information we need. All we have to do now is to fill the below template with required information.
Template:
Our SQL query should look like below:
SELECT *
FROM
(
SELECT SalesYear, SalesMonth,Amount
FROM Sales
) AS SourceTable
PIVOT
(
SUM(Amount )
FOR SalesMonth
IN ( [Jan],[Feb] ,[Mar],
[Apr],[May],[Jun] ,[Jul],
[Aug],[Sep] ,[Oct],[Nov] ,[Dec])
) AS PivotTable;
In the above query we have hard coded the column names. Well it's not fun when you have to specify a number of columns.
However, there is a work arround as follows:
DECLARE #columnList nvarchar (MAX)
DECLARE #pivotsql nvarchar (MAX)
SELECT #columnList = STUFF(
(
SELECT ',' + '[' + SalesMonth + ']'
FROM Sales
GROUP BY SalesMonth
FOR XML PATH( '')
)
,1, 1,'' )
SET #pivotsql =
N'SELECT *
FROM
(
SELECT SalesYear, SalesMonth,Amount
FROM Sales
) AS SourceTable
PIVOT
(
SUM(Amount )
FOR SalesMonth
IN ( ' + #columnList +' )
) AS PivotTable;'
EXEC sp_executesql #pivotsql
Hopefully this tutorial will be a help to someone somewhere.
Enjoy coding.