I have two tables, CustomerCost and Products that look like the following:
I am joining the two tables using the following SQL query:
SELECT custCost.ProductId,
custCost.CustomerCost
FROM CUSTOMERCOST Cost
LEFT JOIN PRODUCTS prod ON Cost.productId =prod.productId
WHERE prod.productId=4
AND (Cost.Customer_Id =2717
OR Cost.Customer_Id IS NULL)
The result of the join is:
joins result
What i want to do is when I pass customerId 2717 it should return only specific customer cost i.e. 258.93, and when customerId does not match then only it should take cost as 312.50
What am I doing wrong here?
You can get your expected output as follows:
SELECT Cost.ProductId,
Cost.CustomerCost
FROM CUSTOMERCOST Cost
INNER JOIN PRODUCTS prod ON Cost.productId = prod.productId
WHERE prod.productId=4
AND Cost.Customer_Id = 2717
However, if you want to allow customer ID to be passed as NULL, you will have to change the last line to AND Cost.Customer_Id IS NULL. To do so dynamically, you'll need to use variables and generate the query based on the input.
The problem in the original query that you have posted is that you have used an alias called custCost which is not present in the query.
EDIT: Actually, you don't even need a join. The CUSTOMERCOST table seems to have both Customer and Product IDs.
You can simply:
SELECT
Cost.ProductId, Cost.CustomerCost
FROM
CUSTOMERCOST Cost
WHERE
Cost.Customer_Id = 2717
AND Cost.productId = 4
You seem to want:
SELECT c.*
FROM CUSTOMERCOST c
WHERE c.productId = 4 AND c.Customer_Id = 2717
UNION ALL
SELECT c.*
FROM CUSTOMERCOST c
WHERE c.productId = 4 AND c.Customer_Id IS NULL AND
NOT EXISTS (SELECT 1 FROM CUSTOMERCOST c2 WHERE c2.productId = 4 AND c2.Customer_Id = 2717);
That is, take the matching cost, if it exists for the customer. Otherwise, take the default cost.
SELECT custCost.ProductId,
custCost.CustomerCost
FROM CUSTOMERCOST Cost
LEFT JOIN PRODUCTS prod
ON Cost.productId =prod.productId
AND (Cost.Customer_Id =2717 OR Cost.Customer_Id IS NULL)
WHERE prod.productId=4
WHERE applies to the joined row. ON controls the join condition.
Outer joins are why FROM and ON were added to SQL-92. The old SQL-89
syntax had no support for them, and different vendors added different,
incompatible syntax to support them.
Related
SELECT
supplies.id,
supplierId,
supplies.date,
supplies.commodity,
supplier_payments.date AS paymentDate,
FROM
supplies
INNER JOIN suppliers ON suppliers.id = supplies.supplierId
LEFT JOIN supplier_payments ON supplier_payments.supplyId = supplies.id
WHERE supplier_payments.isDeleted = 0 AND supplierId = 1
What I am trying is to get all records from supplies table and related records from supplier_payments but the supplier_payments.isDeleted should be equal to 0. What happens now that I only get records from supplies that have at least one supplier payment because of the condition. Is there a way to get all supply records and supply payments with condition?
Consider moving the condition on the LEFT JOINed table to the ON clause of the JOIN:
SELECT
sr.id,
se.supplierId,
se.date,
se.commodity,
sp.date AS paymentDate,
FROM supplies se
INNER JOIN suppliers sr ON sr.id = se.supplierId
LEFT JOIN supplier_payments sp
ON sp.supplyId = se.id
AND sp.isDeleted = 0
WHERE se.supplierId = 1
Side notes:
in a multi-table query, always qualify each column with the table it belongs to, to make the query easier to follow and avoid ambiguity
table aliases make the query easier to read and write
I have to make a list of customer who do not have any invoice but have paid an invoice … maybe twice.
But with my code (stated below) it contains everything from the left join. However I only need the lines highlighted with green.
How should I make a table with only the 2 highlights?
Select paymentsfrombank.invoicenumber,paymentsfrombank.customer,paymentsfrombank.value
FROM paymentsfrombank
LEFT OUTER JOIN debtors
ON debtors.value = paymentsfrombank.value
You only want to select columns from paymentsfrombank. So why do you even join?
select invoice_number, customer, value from paymentsfrombank
except
select invoice_number, customer, value from debtors;
(This requires exact matches as in your example, i.e. same amount for the invoice/customer).
There are two issues in your SQL. First, you need to join on Invoice number, not on value, as joining on value is pointless. Second, you need to only pick those payments where there are no corresponding debts, i.e. when you left-join, the table on the right has "null" in the joining column. The SQL would be something like this:
SELECT paymentsfrombank.invoicenumber,paymentsfrombank.customer,paymentsfrombank.value
FROM paymentsfrombank
LEFT OUTER JOIN debtors
ON debtors.InvoiceNumber = paymentsfrombank.InvoiceNumber
WHERE debtors.InvoiceNumber is NULL
in mysql we usually have this way to flip the relation and extract the rows that dosen't have relation.
Select paymentsfrombank.invoicenumber,paymentsfrombank.customer,paymentsfrombank.value
FROM paymentsfrombank
LEFT OUTER JOIN debtors
ON debtors.value = paymentsfrombank.value where debtors.value is null
You can use NOT EXISTS :
SELECT p.*
FROM paymentsfrombank p
WHERE NOT EXISTS (SELECT 1 FROM debtors d WHERE d.invoice_number = p.invoice_number);
However, the LEFT OUTER JOIN would also work if you add filtered with WHERE Clause to filtered out only missing customers that haven't any invoice information :
SELECT p.invoicenumber, p.customer, p.value
FROM paymentsfrombank P LEFT OUTER JOIN
debtors d
ON d.InvoiceNumber = p.InvoiceNumber
WHERE d.InvoiceNumber IS NULL;
Note : I have used table alias (p & d) that makes query to easier read & write.
I'm taking my first steps in terms of practical SQL use in real life.
I have a few tables with contractual and financial information and the query works exactly as I need - to a certain point. It looks more or less like that:
SELECT /some columns/ from CONTRACTS
Linked 3 extra tables with INNER JOIN to add things like department names, product information etc. This all works but they all have simplish one-to-one relationship (one contract related to single department in Department table, one product information entry in the corresponding table etc).
Now this is my challenge:
I also need to add contract invoicing information doing something like:
inner join INVOICES on CONTRACTS.contnoC = INVOICES.contnoI
(and selecting also the Invoice number linked to the Contract number, although that's partly optional)
The problem I'm facing is that unlike with other tables where there's always one-to-one relationship when joining tables, INVOICES table can have multiple (or none at all) entries that correspond to a single contract no. The result is that I will get multiple query results for a single contract no (with different invoice numbers presented), needlessly crowding the query results.
Essentially I'm looking to add INVOICES table to a query to just identify if the contract no is present in the INVOICES table (contract has been invoiced or not). Invoice number itself could be presented (it is with INNER JOIN), however it's not critical as long it's somehow marked. Invoice number fields remains blank in the result with the INNER JOIN function, which is also necessary (i.e. to have the row presented even if the match is not found in INVOICES table).
SELECT DISTINCT would look to do what I need, but I seemed to face the problem that I need to levy DISTINCT criteria only for column representing contract numbers, NOT any other column (there can be same values presented, but all those should be presented).
Unfortunately I'm not totally aware of what database system I am using.
Seems like the question is still getting some attention and in an effort to provide some explanation here are a few techniques.
If you just want any contract with details from the 1 to 1 tables you can do it similarily to what you have described. the key being NOT to include any column from Invoices table in the column list.
SELECT
DISTINCT Contract, Department, ProductId .....(nothing from Invoices Table!!!)
FROM
Contracts c
INNER JOIN Departments D
ON c.departmentId = d.Department
INNER JOIN Product p
ON c.ProductId = p.ProductId
INNER JOIN Invoices i
ON c.contnoC = i.contnoI
Perhaps a Little cleaner would be to use IN or EXISTS like so:
SELECT
Contract, Department, ProductId .....(nothing from Invoices Table!!!)
FROM
Contracts c
INNER JOIN Departments D
ON c.departmentId = d.Department
INNER JOIN Product p
ON c.ProductId = p.ProductId
WHERE
EXISTS (SELECT 1 FROM Invoices i WHERE i.contnoI = c.contnoC )
SELECT
Contract, Department, ProductId .....(nothing from Invoices Table!!!)
FROM
Contracts c
INNER JOIN Departments D
ON c.departmentId = d.Department
INNER JOIN Product p
ON c.ProductId = p.ProductId
WHERE
contnoC IN (SELECT contnoI FROM Invoices)
Don't use IN if the SELECT ... list can return a NULL!!!
If you Actually want all of the contracts and just know if a contract has been invoiced you can use aggregation and a case expression:
SELECT
Contract, Department, ProductId, CASE WHEN COUNT(i.contnoI) = 0 THEN 0 ELSE 1 END as Invoiced
FROM
Contracts c
INNER JOIN Departments D
ON c.departmentId = d.Department
INNER JOIN Product p
ON c.ProductId = p.ProductId
LEFT JOIN Invoices i
ON c.contnoC = i.contnoI
GROUP BY
Contract, Department, ProductId
Then if you actually want to return details about a particular invoice you can use a technique similar to that of cybercentic87 if your RDBMS supports or you could use a calculated column with TOP or LIMIT depending on your system.
SELECT
Contract, Department, ProductId, (SELECT TOP 1 InvoiceNo FROM invoices i WHERE c.contnoC = i.contnoI ORDER BY CreateDate DESC) as LastestInvoiceNo
FROM
Contracts c
INNER JOIN Departments D
ON c.departmentId = d.Department
INNER JOIN Product p
ON c.ProductId = p.ProductId
GROUP BY
Contract, Department, ProductId
I would do it this way:
with mainquery as(
<<here goes you main query>>
),
invoices_rn as(
select *,
ROW_NUMBER() OVER (PARTITION BY contnoI order by
<<some column to decide which invoice you want to take eg. date>>) as rn
)
invoices as (
select * from invoices_rn where rn = 1
)
select * from mainquery
left join invoices i on contnoC = i.contnoI
This gives you an ability to get all of the invoice details to your query, also it gives you full control of which invoice you want see in your main query. Please read more about CTEs; they are pretty handy and much easier to understand / read than nested selects.
I still don't know what database you are using. If ROW_NUMBER is not available, I will figure out something else :)
Also with a left join you should use COALESCE function for example:
COALESCE(i.invoice_number,'0')
Of course this gives you some more possibilities, you could for example in your main select do:
CASE WHEN i.invoicenumber is null then 'NOT INVOICED'
else 'INVOICED'
END as isInvoiced
You can use
SELECT ..., invoiced = 'YES' ... where exists ...
union
SELECT ..., invoiced = 'NO' ... where not exists ...
or you can use a column like "invoiced" with a subquery into invoices to set it's value depending on whether you get a hit or not
I have an e-commerce website (using VirtueMart) and I sell products that consist child products. When a product is a parent, it doesn't have ParentID, while it's children refer to it. I know, not the best logic but I didn't create it.
My SQL is very basic and I believe I ask for something quite easy to achieve
Select products that have children.
Sort results by prices (ASC/DSC).
SELECT * FROM Products INNER JOIN Prices ON Products.ProductID = Prices.ProductID ORDER BY Products.Price [ASC/DSC]
Explanation:
SELECT - Select (Get/Retrieve)
* - ALL
FROM Products - Get them from a DB Table named "Products".
INNER JOIN Prices - Selects all rows from both tables as long as there is a match between the columns in both tables. Rather, JOIN DB Table "Products" with DB Table "Prices".
ON - Like WHERE, this defines which rows will be checked for matches.
Products.ProductID = Prices.ProductID - Your match criteria. Get the rows where "ProductID" exists in both DB Tables "Products" and "Prices".
ORDER BY Products.Price [ASC/DSC] - Sorting. Use ASC for Ascending, DSC for Descending.
This table design is subpar for a number of reasons. First, it appears that the value 0 is being used to indicate lack of a parent (as there's no 0 ID for products). Typically this will be a NULL value instead.
If it were a NULL value, the SQL statement to get everything without a parent would be as simple as this:
SELECT * FROM Products WHERE ParentID IS NULL
However, we can't do that. If we make the assumption that 0 = no parent, we can do this:
SELECT * FROM Products WHERE ParentID = 0
However, that's a dangerous assumption to make. Thus, the correct way to do this (given your schema above), would be to compare the two tables and ensure that the parentID exists as a ProductID:
SELECT a.*
FROM Products AS a
WHERE EXISTS (SELECT * FROM Products AS b WHERE a.ID = b.ParentID)
Next, to get the pricing, we have to join those two tables together on a common ID. As the Prices table seems to reference a ProductID, we can use that like so:
SELECT p.ProductID, p.ProductName, pr.Price
FROM Products AS p INNER JOIN Prices AS pr ON p.ProductID = pr.ProductID
WHERE EXISTS (SELECT * FROM Products AS b WHERE p.ID = b.ParentID)
ORDER BY pr.Price
That might be sufficient per the data you've shown, but usually that type of table structure indicates that it's possible to have more than one price associated with a product (we're unable to tell whether this is true based on the quick snapshot).
That should get you close... if you need something more, we'll need more detail.
use the below script if you are using ssms.
SELECT pd.ProductId,ProductName,Price
FROM product pd
LEFT JOIN price pr ON pd.ProductId=pr.ProductID
WHERE EXISTS (SELECT 1 FROM product pd1 WHERE pd.productID=pd1.ParentID)
ORDER BY pr.Price ASC
Note :neither of your parent product have price in price table. If you want the sum of price of their child product use the below script.
SELECT pd.ProductId,pd.ProductName,SUM(ISNULL(pr.Price,0)) SUM_ChildPrice
FROM product pd
LEFT JOIN product pd1 ON pd.productID=pd1.ParentID
LEFT JOIN price pr ON pd1.ProductId=pr.ProductID
GROUP BY pd.ProductId,pd.ProductName
ORDER BY pr.Price ASC
You will have to use self-join:
For example:
SELECT * FROM products parent
JOIN products children ON parent.id = children.parent_id
JOIN prices ON prices.product_id = children.id
ORDER BY prices.price
Because we are using JOIN it will filter out all entries that don't have any children.
I haven't tested it, I hope it would work.
I am new at access SQL and i need help with some query. What i want is to find those customers that prefer a car (manufacturer and model) from prefer_to_buy AND prefer_to_rent that no one else prefer.
For example if 2 customers prefer toyota aygo must not be in the result table.
customer(customer_id,name)
prefer_to_buy(customer_id,manufacturer,model)
prefer_to_rent(customer_id, manufacturer,model)
I have tried a lot of ways including exists and i know there must be about 2-3 subqueries but i cant get it to work, any ideas?
Your problem definition is very vague, so the answer is also sort of generic. You should try to create a Left Outer Join on customer table and, for example, a "prefer_to_buy" Table using customer_id as a join field, and include:
customer_id,name from the left table and manufacturer,model from the right table. The same logic applies to prefer_to_rent Table: you can actually combine these 3 Tables in a single Access SQL query using the aforementioned Outer Joins.
Hope this may help. Best regards,enter code here
There are a couple of parts to cover here. First, you could use the union operator to treat prefer_to_buy and prefer_to_rent as a single table (possibly with an additional literal "column" to indicate preference type). Once you've done this, you could use the exists operator to make sure no other customers prefer this car:
SELECT c.name, p.manufacturer, p.model
FROM customer c
JOIN (SELECT customer_id, manufacturer, model
FROM prefer_to_buy
UNION
SELECT customer_id, manufacturer, model
FROM prefer_to_buy) p ON c.customer_id = p.customer_id
WHERE NOT EXISTS (SELECT *
FROM prefer_to_buy pb
WHERE c.customer_id != pb.customer_id AND
p.manufacturer = pb.manufacturer AND
p.model = pb.model) AND
NOT EXISTS (SELECT *
FROM prefer_to_rent pr
WHERE c.customer_id != pr.customer_id AND
p.manufacturer = pr.manufacturer AND
p.model = pr.model)
First you need to do to two joins one on prefer_to_buy AND one on prefer_to_rent.
Next, you need to check if any one else would like the same manufacturer and model. Do this with a exist
SELECT *
FROM customer AS c
JOIN prefer_to_buy AS pb ON c.customer_id = pb.customer_id
JOIN prefer_rent AS pr ON c.customer_id = pr.customer_id
WHERE NOT EXISTS ( SELECT 'x' FROM prefer_to_buy AS pb1 WHERE pb.manufacturer = pb1.manufacturer AND pb.model = pb1.model AND pb.customer_id <> pb1.customer_id)
AND NOT EXISTS ( SELECT 'x' FROM prefer_to_rent AS pr1 WHERE pb.manufacturer = pr1.manufacturer AND pb.model = pr1.model AND pb.customer_id <> pr1.customer_id)