I am new to SQL and databases and am trying to learn about queries and the different relationship types by challenging myself.
I am not sure if I drew this correctly but I basically have two tables. Supplier and Brand. One brand can have many suppliers but one supplier may also supply to many brands.
I created a third table which holds these relationships which is called Supplier_Brand.
SELECT supplier_name, brand.brand_name
FROM Brand
INNER JOIN Supplier_Brand
ON Brand.brand_id = Supplier_Brand.brand_id
INNER JOIN Supplier
ON Supplier.supplier_id = Supplier_Brand.supplier_id;
I managed to join them with the query above and get the following output:
However, I would like to only show the supplier that delivers to more than one brand ( what is shown in the green box ) I have tried all sort of things with GROUP BY and HAVING and count but I am not able to get it right. How could I solve this?
You can use CTE (Common Table Expression) to achieve your expectation.
WITH id_of_multiple_brand AS (SELECT supplier_id
FROM Brand
INNER JOIN Supplier_Brand
ON Brand.brand_id = Supplier_Brand.brand_id
INNER JOIN Supplier
ON Supplier.supplier_id = Supplier_Brand.supplier_id
GROUP BY supplier_id
HAVING count(brand.brand_name) > 1)
SELECT supplier_name, brand.brand_name
FROM Brand
INNER JOIN Supplier_Brand
ON Brand.brand_id = Supplier_Brand.brand_id
INNER JOIN Supplier
ON Supplier.supplier_id = Supplier_Brand.supplier_id
where supplier_id in (select supplier_id from id_of_multiple_brand);
We can use MIN() and MAX() here as analytic functions:
WITH cte AS (
SELECT s.supplier_name, b.brand_name,
MIN(b.brand_name) OVER (PARTITION BY s.supplier_name) AS min_brand_name,
MAX(b.brand_name) OVER (PARTITION BY s.supplier_name) AS max_brand_name
FROM Brand b
INNER JOIN Supplier_Brand sb ON b.brand_id = sb.brand_id
INNER JOIN Supplier s ON s.supplier_id = sb.supplier_id
)
SELECT supplier_name, brand_name
FROM cte
WHERE min_brand_name <> max_brand_name
ORDER BY supplier_name, brand_name;
Related
I have samples, sample_products, products, orders and order_products.
Samples <=> Products (through sample_products)
Order <=> Products (through order_products).
There is no connection between Order and Samples.
Now I need to find the most used Samples on an Order. This is particularly a problem because if we for example have a package of 2 products - product A and product B, an order needs to contain both of them, not only product A or not only product B.
An order has to contain only and exactly those 2 products to be considered a sample.
I tried joining them like this but this leads to the problem I mentioned before - it does not ensure the order does not contain other products or that both A and B are present.
SELECT * FROM samples
INNER JOIN sample_products ON sample_products.sample_id = samples.id
INNER JOIN products ON products.id = sample_products.product_id
INNER JOIN order_products ON order_products.product_id = products.id
INNER JOIN orders ON orders.id = order_products.order_id
How can I make sure that it only joins the table together if both product A and B are present?
If you want to count full sample set (if sample1 consits from A,B,C -> count oreder with A,B,C), you can use number of product for join:
SELECT order_sample_count.sample_id,
COUNT(order_sample_count.order_id) as sample_use
FROM
(
SELECT sample_id, count(product_id) as semple_numbers
FROM
(
SELECT DISTINCT sample_id, sample_products.product_id
FROM samples
INNER JOIN sample_products ON sample_products.sample_id = samples.id
) AS sample_distinct
GROUP BY sample_id
) AS semple_count
INNER JOIN
)
SELECT order_id, sample_id, count(product_id) as semple_numbers
FROM
(
SELECT DISTINCT order_products.order_id, sample_products.sample_id, order_products.product_id
FROM order_products
INNER JOIN sample_products ON sample_products.product_id = order_products.product_id
) AS order_sample_distinct
GROUP BY order_id, sample_id
) AS order_sample_count ON semple_count.sample_id = order_sample_count.sample_id
AND semple_count.semple_numbers = order_sample_count.semple_numbers
GROUP BY order_sample_count.sample_id
I am stuck on this and I am relatively new to SQL.
Here is the question we were given:
List the productname and vendorid for all products that we have
purchased from more than one vendor (Hint: you’ll need a Self-Join and
an additional INNER JOIN to solve, don't forget to remove any
duplicates!!)
Here is a screenshot of tables we are working with:
Here is what I have.....I know it is wrong. It works to a degree, just not exactly how the prof wants it.
SELECT DISTINCT productname, product_vendors.vendorid
FROM products INNER JOIN Product_Vendors
ON products.PRODUCTNUMBER = PRODUCT_VENDORS.PRODUCTNUMBER
INNER JOIN vendors ON Product_Vendors.VENDORID = vendors.VENDORID
ORDER BY products.PRODUCTNAME;
Expected output provided the prof:
I agree with #jarlh that additional information would be helpful- i.e. are there triplicates in the data or just duplicates, etc.
That said, this should get your started
SELECT
c.productname AS 'Product'
,a.vendorid AS 'Vendor1'
,b.vendorid AS 'Vendor2'
FROM
product_vendors AS a
JOIN
product_vendors AS b
ON
a.productnumber = b.productnumber
AND a.vendorid <> b.vendorid
JOIN
dbo.products AS c
ON
a.productnumber = c.productnumber
This will limit the population of 'Product Vendors' just to products with unmatching vendors.
From there you are joining to products to pull back product name.
Also- work on coding format, clean code makes the dream work :)
The solution to this problem is usually to count vendors per product with COUNT OVER and only stick with products with more than one. Simply:
select productname, vendorid
from
(
select
p.productname,
pv.vendorid,
count(*) over (partition by product) as cnt
from products p
join product_vendors pv using (productnumber)
)
where cnt > 1;
If this shall be done without window functions, then one option is to aggregate product_vendors and use this result:
select p.productname, pv.vendorid
from
(
select productid
from product_vendors
group by productname
having count(*) > 1
) px
join products p using (productid)
join product_vendors pv using (productid);
or check whether exists another vendor for the product:
select
p.productname,
pv.vendorid,
count(*) over (partition by product) as cnt
from products p
join product_vendors pv on pv.productnumber = p.productnumber
where exists
(
select *
from product_vendors other
where other.productnumber = pv.productnumber
and other.vendorid <> pv.vendorid
);
In neither of these approaches I see the need to eliminate duplicates, as there should be one row per product in products and one row per product and vendor in product_vendors. So I guess what your prof was thinking of is:
select distinct
p.productname,
pv.vendorid
from products p
join product_vendors pv on pv.productnumber = p.productnumber
join product_vendors other on other.productnumber = pv.productnumber
and other.vendorid <> pv.vendorid
This, however, is an approach I don't recommend. You'd combine all vendors for a product (e.g. with 10 vendors for one product you already have 45 combinations for that product only, if I'm not mistaken). So you'd create a large intermediate result only to dismiss most of it with DISTINCT later. Don't do that. Remember: SELECT DISTINCT is often an indicator for a poorly written query (i.e. unnecessary joins leading to too many combinations you are not actually interested in).
SELECT DISTINCT p.name AS product, v.id
FROM products p
INNER JOIN product_vendors pv ON p.id = pv.productid
INNER JOIN product_vendors pv2 ON pv.productid = pv2.productid AND pv.vendorid != pv2.vendorid
INNER JOIN vendors v ON v.id = pv.vendorid
ORDER BY p.name
If I have two tables, like this for example:
Table 1 (products)
id
name
price
agentid
Table 2 (agent)
userid
name
email
How do I get a result set from products that include the agents name and email, meaning that products.agentid = agent.userid?
How do I join for example SELECT WHERE price < 100?
Edited to support price filter
You can use the INNER JOIN clause to join those tables. It is done this way:
select p.id, p.name as ProductName, a.userid, a.name as AgentName
from products p
inner join agents a on a.userid = p.agentid
where p.price < 100
Another way to do this is by a WHERE clause:
select p.id, p.name as ProductName, a.userid, a.name as AgentName
from products p, agents a
where a.userid = p.agentid and p.price < 100
Note in the second case you are making a natural product of all rows from both tables and then filtering the result. In the first case you are directly filtering the result while joining in the same step. The DBMS will understand your intentions (regardless of the way you choose to solve this) and handle it in the fastest way.
This is a very rudimentary INNER JOIN:
SELECT
products.name AS productname,
price,
agent.name AS agentname
email
FROM
products
INNER JOIN agent ON products.agentid = agent.userid
I recommend reviewing basic JOIN syntax and concepts. Here's a link to Microsoft's documentation, though what you have above is pretty universal as standard SQL.
Note that the INNER JOIN here assumes every product has an associated agentid that isn't NULL. If there are NULL agentid in products, use LEFT OUTER JOIN instead to return even the products with no agent.
select p.name productname, p.price, a.name as agent_name, a.email
from products p
inner join agent a on (a.userid = p.agentid)
This is my join for slightly larger tables in Prod.Hope it helps.
SELECT TOP 1000 p.[id]
,p.[attributeId]
,p.[name] as PropertyName
,p.[description]
,p.[active],
a.[appId],
a.[activityId],
a.[Name] as AttributeName
FROM [XYZ.Gamification.V2B13.Full].[dbo].[ADM_attributeProperty] p
Inner join [XYZ.Gamification.V2B13.Full].[dbo].[ADM_activityAttribute] a
on a.id=p.attributeId
where a.appId=23098;
select ProductName=p.[name]
, ProductPrice=p.price
, AgentName=a.[name]
, AgentEmail=a.email
from products p
inner join agent a on a.userid=p.agentid
If you don't want to use inner join (or don't have possibility to do it!) and would combine rows, you can use a cross join :
SELECT *
FROM table1
CROSS JOIN table2
or simply
SELECT *
FROM table1, table2
I'm using SQL Server. This statement lists my products per menu:
SELECT menuname, productname
FROM [web].[dbo].[tblMenus]
FULL OUTER JOIN [web].[dbo].[tblProductsRelMenus]
ON [tblMenus].Id = [tblProductsRelMenus].MenuId
FULL OUTER JOIN [web].[dbo].[tblProducts]
ON [tblProductsRelMenus].ProductId = [tblProducts].ProductId
LEFT JOIN [web].[dbo].[tblOrderDetails]
ON ([tblProducts].Id = [tblOrderDetails].ProductId)
GROUP BY [tblProducts].ProductName
Some products don't have menus and vice versa. I use the following to establish what has been sold of each product.
SELECT [tblProducts].ProductName, SUM([tblOrderDetails].Ammount) as amount
FROM [web].[dbo].[tblProducts]
LEFT JOIN [web].[dbo].[tblOrderDetails]
ON ([tblProducts].ProductId = [tblOrderDetails].ProductId)
GROUP BY [tblProducts].ProductName
What I want to do is complement the top table with an amount column. That is, I want a table with the same number of rows as in the first table above but with an amount value if it exists, otherwise null.
I can't figure out how to do this. Any suggestions?
If I am not missing anything, the second query could be simplified, then incorporated into the first query like this:
SELECT
m.menuname,
p.productname,
t.amount
FROM [web].[dbo].[tblMenus] m
FULL JOIN [web].[dbo].[tblProductsRelMenus] pm ON m.Id = pm.MenuId
FULL JOIN [web].[dbo].[tblProducts] p ON pm.ProductId = p.ProductId
LEFT JOIN (
SELECT ProductId, SUM(Amount) as amount
FROM [web].[dbo].[tblOrderDetails]
GROUP BY ProductId
) t ON p.ProducId = t.ProductId
I want to make a query to list cats that took longer than average cats to sell?
I have five tables:
Animal, Sale, AnimalOrderItem, AnimalOrder, and SaleAnimal
Animal table: AnimalID, Name, Category
(cat, dog, fish)
SaleAnimal table: SaleID, AnimalID,
SalePrice
Sale table: SaleID, date, employeeID,
CustomerID
AnimalOrderItem table: OrderID,
AnimalID, cost
AnimalOrder: OrderID, OrderDate,
ReceivingDate,
SupplierID, ShippingCost, EmployeeID
There is other tables I don’t think they have an effect on the query.
I thought of the following ... make a query to calculate days to sell for all ex.:
[SaleDate]-[ReceiveDate] AS DaysToSell
Have the INNER JOIN built:
Sale INNER JOIN ((AnimalOrder INNER JOIN (Animal INNER JOIN AnimalOrderItem
ON Animal.AnimalID = AnimalOrderItem.AnimalID) ON AnimalOrder.
OrderID = AnimalOrderItem.OrderID) INNER JOIN SaleAnimal ON Animal.
AnimalID = SaleAnimal.AnimalID) ON Sale.SaleID = SaleAnimal.SaleID
Create another query based on the above query
SELECT AnimalID, Name, Category, DaysToSell
WHERE Category="Cat" AND DaysToSell>
(SELECT Avg(DaysToSell)
FROM the earlier query
WHERE Category="Cat"
ORDER BY DaysToSell DESC;
After running the query it I got error saying
ORA-00921: unexpected end of SQL
command
Any suggestions! please
Queries can be combined with a subquery. For example,
select *
from (
select *
from mytable
) subquery
Applying this pattern to your problem seems fairly straightforward.
I don't see the closed bracket that matches with the select avg
Ok, I've come up with this:
SELECT AnimalID, Name, Category,
[SaleDate]-[ReceiveDate] AS DaysToSell
FROM Sale INNER JOIN ((AnimalOrder INNER JOIN (Animal INNER JOIN AnimalOrderItem ON Animal.AnimalID = AnimalOrderItem.AnimalID) ON AnimalOrder.OrderID = AnimalOrderItem.OrderID)
INNER JOIN SaleAnimal ON Animal.AnimalID = SaleAnimal.AnimalID) ON Sale.SaleID = SaleAnimal.SaleID
WHERE Category = "Cat"
AND ([SaleDate]-[ReceiveDate]) > (SELECT AVG([SaleDate]-[ReceiveDate])
FROM Sale INNER JOIN ((AnimalOrder INNER JOIN (Animal INNER JOIN AnimalOrderItem ON Animal.AnimalID = AnimalOrderItem.AnimalID) ON AnimalOrder.OrderID = AnimalOrderItem.OrderID)
INNER JOIN SaleAnimal ON Animal.AnimalID =SaleAnimal.AnimalID) ON Sale.SaleID = SaleAnimal.SaleID
WHERE Category = "Cat")
ORDER BY ([SaleDate]-[ReceiveDate]) DESC;