I have two tables. One with properties and one with buildings. Each property is associated with 0 to theoretically infinite amounts of buildings. Right now i have a code like this:
Select Property.ID, Building.Number
From Properties
Left Join Buildings on Buildings.pID = Property.ID
This returns a table of all buildings with their associated property. This however means, that all properties appear as many times, as they have buildings.
What i want is a result, where each property has its buildings in the same row as it self, so it becomes a result of properties, with their buildings, and not a result of buildings, with their properties.
EDIT: I should probably specify, that this is a server i only have read access on.
In sql server, you can use STUFF fuctionality for combining the resultset.
SELECT P.ID
,STUFF((SELECT ', ' + CAST(b.Number AS VARCHAR(10)) [text()]
FROM Buildings b
WHERE b.pID = P.ID
FOR XML PATH(''), TYPE)
.value('.','NVARCHAR(MAX)'),1,2,' ') BuildingNumbers
FROM Properties p
If the properties really are able to have an infinite amount of buildings then this will become really hard. You will have to create a table with an infinite amount of rows (one for each potential building), and set all of them to NULL except where there are buildings.
You can't have a dynamic amount of columns. It will have to be set beforehand. There are suboptimal workarounds, but they are all very contrary to database normalization.
edit: if it's just for the results of a query you could use PIVOT()
Related
I currently have a schema set up in the following manner:
The table tblCategoryRiskArea is set up as an intermediate table for the many-to-many relationship that can exist between Categories and RiskAreas.
Within the tblBase table, I would like to make it so that the RiskArea choices are dependant upon the Category choice. MS Access allows you to set a Lookup for a field in a table based upon a Row Source SQL statement. I am having trouble figuring out the correct SQL statement to define the Row Source for RiskArea dependant upon Category. This:
SELECT tblRiskAreas.RiskAreaID, tblRiskAreas.RiskArea
FROM tblRiskAreas INNER JOIN
((tblCategories INNER JOIN tblBase
ON tblCategories.CategoryId = tblBase.Category)
INNER JOIN tblCategoryRiskArea
ON tblCategories.CategoryId = tblCategoryRiskArea.Category)
ON (tblRiskAreas.RiskAreaID = tblCategoryRiskArea.RiskArea)
AND (tblRiskAreas.RiskAreaID = tblBase.RiskArea)
WHERE (((tblCategoryRiskArea.Category)=[tblBase]![Category]))
ORDER BY tblRiskAreas.RiskAreaID;
is the best I've come up with so far, using MS Access' Query Builder, so all of the Inner Joins have been created just by my having defined the relationships between the tables and dragging them into the Query Builder. This query returns nothing, however.
I suspect that it may have something to do with the circular nature of the relationships I set up?
Thank you.
Edited: tblRiskArea contains 4 RiskAreas, as follows:
Environmental
Health
Safety
Security
Each Category can fall into one or two of these RiskAreas, so the tblCategoryRiskArea creates the relationship bewtween them.
First remove Category and RiskArea from tblBase and replace them for CategoriRiskAreaID
You will show in your form 2 combos. First combo Catagory data source:
Select CategoryId,Category from tblCategories
Second combo Risk Areas data source:
Select a.CategoryRiskId, b.RiskArea
from tblCategoryRiskArea a
inner join tblRiskArea b
where a.RiskAreaId=b.RiskAreaId
AND a.category = #ComboBoxCategorySelectedItem
Now you have the value to insert in tblBase, ComboBoxSelectedItem is tblCategoryRiskArea.CategoryRiskId
I've seen several questions about how to pull together multiple rows into a single comma-separated column with t-sql. I'm trying to map those examples to my own case in which I also need to bring columns from two tables together referencing a junction table. I can't make it work. Here's the query I have:
WITH usersCSV (userEmails, siteID)
AS (SELECT usersSites.siteID, STUFF(
(SELECT ', ' + users.email
FROM users
WHERE usersSites.userID = users.id
FOR XML PATH ('')
GROUP BY usersSites.userID
), 1, 2, '')
FROM usersSites
GROUP BY usersSites.siteID
)
SELECT * FROM usersCSV
The hard stuff here is based on this answer. I've added the WITH which, as I understand it, creates a sort of temporary table (I'm sure it's actually more complicated than that, but humor me.) to hold the values. Obviously, I don't need this just to select the values, but I'm going to be joining this with another table later. (The whole of what I need to do is still more complicated than what I'm trying to do here.)
So, I'm creating a temporary table named usersCSV with two columns which I'm filling by selecting the siteID column from my usersSites table (which is the junction table between users and sites) and selecting ', ' + users.email from my users table which should give me the email address preceded by a comma and space. Then, I chop the first two characters off that using STUFF and group the whole thing by usersSites.siteID.
This query gives me an error identifying line 5 as the problem area:
Column 'usersSites.userID' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.
Why should this matter since the column in question is actually in the WHERE rather than the SELECT as is stated in the error? How can I fix it? I need only the users with an ID that matches an ID in the junction table. I've got tons of users that aren't mapped in that table and have no need to select them.
tl;dr- I need a temp table with distinct sites in one column and a comma-separated list of the email addresses of related users in the other. These two pieces of data come from other tables and will be put together using a junction table on the primary keys of those two tables. Hope that makes sense.
select distinct us.siteId,
STUFF((select ', ' + u.email
from users u
join usersSites us2 on us2.userId = u.userId
where us2.siteId = us.siteId
for xml path('')), 1, 2, '')
from usersSites us
SQL Fiddle
I have two tables, tabSparePart and tabSparePartCategory. Every spare part belongs to a spare part category. I need all spare parts that belong to a specific category. But the problem is that a spare part category could be a "subcategory" of another, they reference each other (the "main categories" have 'null' in this FK column).
Let's say I need all spare parts with fiSparePartCategory=1 and all spare parts that belong to a category that is a "subcategory" of category=1.
How to write the SQL query that returns all spare parts regardless of how many levels of subcategories there are. I hope you understand my requirement.
The following is an illustration of what I have. How to make it dynamic so that it works regardless of the number of subcategories?
Thanks, Tim
Link to image: http://www.bilder-hochladen.net/files/4709-lg-jpg.html
EDIT: Following is an other static approach which works when there is only one level of subcategory:
SELECT SparePartName
FROM tabSparePart
WHERE (fiSparePartCategory IN
(SELECT idSparePartCategory
FROM tabSparePartCategory
WHERE (idSparePartCategory = 1) OR
(fiSparePartCategory = 1)))
You can use a recursive Common Table Expression for this.
In your case, you would need to get all sparepart category ids for a specific main category id and join that with the spareparts. Something like this:
WITH SparePartCategories(CategoryId) AS
(
SELECT c.idSparePartCategory
FROM tabSparePartCategory c
WHERE c.idSparePartCategory = 1
UNION ALL
SELECT c.idSparePartCategory
FROM tabSparePartCategory c
JOIN SparePartCategories parent ON c.fiSparePartCategory = parent.CategoryId
)
SELECT sp.SparePartName
FROM tabSparePart sp
JOIN SparePartCategories spc ON sp.fiSparePartCategory = spc.CategoryId
I'm having an SQL query (MSSQLSERVER) where I add columns to the resultset using subselects:
SELECT P.name,
(select count(*) from cars C where C.type = 'sports') AS sportscars,
(select count(*) from cars C where C.type = 'family') AS familycars,
(select count(*) from cars C where C.type = 'business') AS businesscars
FROM people P
WHERE P.id = 1;
The query above is just from a test setup that's a bit nonsense, but it serves well enough as example I think. The query I'm actually working on spans a number of complex tables which only distracts from the issue at hand.
In the example above, each record in the table "people" also has three additional columns: "wantsSportscar", "wantsFamilycar" and "wantsBusinesscar". Now what I want to do is only do the subselect of each additional column if the respective "wants....." field in the people table is set to "true". In other words, I only want to do the first subselect if P.wantsSportscar is set to true for that specific person. The second and third subselects should work in a similar manner.
So the way this query should work is that it shows the name of a specific person and the number of models available for the types of cars he wants to own. It might be worth noting that my final resultset will always only contain a single record, namely that of one specific user.
It's important that if a person is not interested in a certain type of cars, that the column for that type will not be included in the final resultset. An example to be sure this is clear:
If person A wants a sportscar and a familycar, the result would include the columns "name", "sportscars" and "familycars".
If person B wants a businesscar, the result would include the columns "name" and "businesscar".
I've been trying to use various combinations with IF, CASE and EXISTS statements, but so far I've not been able to get a syntactically correct solution. Does anyone know if this is even possible? Note that the query will be stored in a Stored Procedure.
In your case, there are 8 column layouts possible and to do this, you will need 8 separate queries (or build your query dynamically).
It's not possible to change the resultset layout within a single query.
Instead, you may design your query as follows:
SELECT P.name,
CASE WHEN wantssport = 1 THEN (select count(*) from cars C where C.type = 'sports') ELSE NULL END AS sportscars,
CASE WHEN wantsfamily = 1 THEN (select count(*) from cars C where C.type = 'family') ELSE NULL END AS familycars,
CASE WHEN wantsbusiness = 1 THEN (select count(*) from cars C where C.type = 'business') ELSE NULL END AS businesscars
FROM people P
WHERE P.id = 1
which will select NULL in appropriate column if a person doesn't want it, and parse these NULL's on client side.
Note that relational model answers the queries in terms of relations.
In your case, the relation is as follows: "this person needs are satisifed with this many sport cars, this many business cars and this many family cars".
Relational model always answers this specific question with a quaternary relation.
It doesn't omit any of the relation members: instead, it just sets them to NULL which is the SQL's way to show that the member of a relation is not defined, applicable or meaningful.
I'm mostly an Oracle guy but there's a high chance the same applies. Unless I've misunderstood, what you want is not possible at that level - you will always have a static number of columns. Your query can control if the column is empty but since in the outer-most part of the query you have specified X number of columns, you are guaranteed to get X columns in your resultset.
As I said, I am unfamiliar with MS SQL Server but I'm guessing there will be some way of executing dynamic SQL, in which case you should research that since it should allow you to build a more flexible query.
You may be able to do what you want by first selecting the values as separate rows into a temp table, then doing a PIVOT on that table (turning the rows into columns).
It's important that if a person is not
interested in a certain type of cars,
that the column for that type will not
be included in the final resultset. An
example to be sure this is clear:
You will not be able to do it in plain SQL. I suggest you just make this column NULL or ZERO.
If you want the query to be dynamically expand when new cars are added, then PIVOTing could help you somewhat.
There are three fundamentals you want to learn to make this work easy. The first is data normalization, the second is GROUP BY, and the third is PIVOT.
First, data normalization. Your design of the people table is not in first normal form. The columns "wantsports", "wantfamily", "wantbusiness" are really a repeating group, although they may not look like one. If you can modify the table design, you will find it advantageous to create a third table, lets call it "peoplewant", with two key columns, personid and cartype. I can go into detail about why this design will be more flexible and powerful if you like, but I'm going to skip that for now.
On to GROUP BY. This allows you to produce a result that summarizes each group in one row of the result.
SELECT
p.name,
c.type,
c.count(*) as carcount
FROM people p,
INNER JOIN peoplewant pw ON p.id = pw.personid
INNER JOIN cars c on pw.cartype = c.type
WHERE
p.id = 1
GROUP BY
p.name,
c.type
This (untested) query gives you the result you want, except that the result has a separate row for each car type the person wants.
Finally, PIVOT. The PIVOT tool in your DBMS allows you to turn this result into a form where there is just one row for the person, and there is a separate column for each of the cartypes wanted by that person. I haven't used PIVOT myself, so I'll let somebody else edit this response to provide an example using PIVOT.
If you use the same technique to retrieve data for multiple people in one sweep, keep in mind that a column will appear for each wanted type that any person wants, and zeroes will appear in the PIVOT result for persons who do not want a car type that is in the result columns.
Just came across this post through a google search, so I realize I'm late to this party by a bit, but .. sure this really is possible to do... however, I wouldn't suggest actually doing it this way because it's usually considered a Very Bad Thing (tm).
Dynamic SQL is your answer.
Before I say how to do it, I want to preface this with, Dynamic SQL is a very dangerous thing, if you aren't sanitizing your input from the application.
So, therefore, proceed with caution:
declare #sqlToExecute nvarchar(max);
declare #includeSportsCars bit;
declare #includeFamilyCars bit;
declare #includeBusinessCars bit;
set #includeBusinessCars = 1
set #includeFamilyCars = 1
set #includeSportsCars = 1
set #sqlToExecute = 'SELECT P.name '
if #includeSportsCars = 1
set #sqlToExecute = #sqlToExecute + '(select count(*) from cars C where C.type = ''sports'') AS sportscars, ';
if #includeFamilyCars = 1
set #sqlToExecute = #sqlToExecute + '(select count(*) from cars C where C.type = ''family'') AS familycars, ';
if #includeBusinessCars = 1
set #sqlToExecute = #sqlToExecute + '(select count(*) from cars C where C.type = ''business'') AS businesscars '
set #sqlToExecute = #sqlToExecute + ' FROM people P WHERE P.id = 1;';
exec(#sqlToExecute)
I have a PRODUCTS table, and each product can have multiple attributes so I have an ATTRIBUTES table, and another table called ATTRIBPRODUCTS which sits in the middle. The attributes are grouped into classes (type, brand, material, colour, etc), so people might want a product of a particular type, from a certain brand.
PRODUCTS
product_id
product_name
ATTRIBUTES
attribute_id
attribute_name
attribute_class
ATTRIBPRODUCTS
attribute_id
product_id
When someone is looking for a product they can select one or many of the attributes. The problem I'm having is returning a single product that has multiple attributes. This should be really simple I know but SQL really isn't my thing and past a certain point I get a bit lost in the logic. The problem is I'm trying to check each attribute class separately so I want to end up with something like:
SELECT DISTINCT products.product_id
FROM attribproducts
INNER JOIN products ON attribproducts.product_id = products.product_id
WHERE (attribproducts.attribute_id IN (9,10,11)
AND attribproducts.attribute_id IN (60,61))
I've used IN to separate the blocks of attributes of different classes, so I end up with the products which are of certain types, but also of certain brands. From the results I've had it seems to be that AND between the IN statements that's causing the problem.
Can anyone help a little? I don't have the luxury of completely refactoring the database unfortunately, there is a lot more to it than this bit, so any suggestions how to work with what I have will be gratefully received.
Take a look at the answers to the question SQL: Many-To-Many table AND query. It's the exact same problem. Cletus gave there 2 possible solutions, none of which very trivial (but then again, there simply is no trivial solution).
SELECT DISTINCT products.product_id
FROM products p
INNER JOIN attribproducts ptype on p.product_id = ptype.product_id
INNER JOIN attribproducts pbrand on p.product_id = pbrand.product_id
WHERE ptype.attribute_id IN (9,10,11)
AND pbrand.attribute_id IN (60,61)
Try this:
select * from products p, attribproducts a1, attribproducts a2
where p.product_id = a1.product_id
and p.product_id = a2.product_id
and a1.attribute_id in (9,10,11)
and a2.attribute_id in (60,61);
This will return no rows because you're only counting rows that have a number that's (either 9, 10, 11) AND (either 60, 61).
Because those sets don't intersect, you'll get no rows.
If you use OR instead, it'll give products with attributes that are in the set 9, 10, 11, 60, 61, which isn't what you want either, although you'll then get multiple rows for each product.
You could use that select as an subquery in a GROUP BY statement, grouping by the quantity of products, and order that grouping by the number of shared attributes. That will give you the highest matches first.
Alternatively (as another answer shows), you could join with a new copy of the table for each attribute set, giving you only those products that match all attribute sets.
It sounds like you have a data schema that is GREAT for storage but terrible for selecting/reporting. When you have a data structure of OBJECT, ATTRIBUTE, OBJECT-ATTRIBUTE and OBJECT-ATTRIBUTE-VALUE you can store many objects with many different attributes per object. This is sometime referred to as "Vertical Storage".
However, when you want to retrieve a list of objects with all of their attributes values, it is an variable number of joins you have to make. It is much easier to retrieve data when it is stored horizonatally (Defined columns of data)
I have run into this scenario several times. Since you cannot change the existing data structure. My suggest would be to write a "layer" of tables on top. Dynamically create a table for each object/product you have. Then dynamically create static columns in those new tables for each attribute. Pretty much you need to "flatten" your vertically stored attribute/values into static columns. Convert from a vertical architecture into a horizontal ones.
Use the "flattened" tables for reporting, and use the vertical tables for storage.
If you need sample code or more details, just ask me.
I hope this is clear. I have not had much coffee yet :)
Thanks,
- Mark
You can use multiple inner joins -- I think this would work:
select distinct product_id
from products p
inner join attribproducts a1 on a1.product_id=p.product_id
inner join attribproducts a2 on a1.product_id=p.product_id
where a1.attribute_id in (9,10,11)
and a2.attribute_id in (60,61)