I am using MS Access 2013.
I am trying to selecting the number and name from Salesperson table. Number, name and postcode from Customers table as well as all the information from the CarSale table all within the past month and order by salesperson no.
I have come up with the following
SELECT CS.carNo, CS.dateOfSale, SA.salespersonNo, SA.name AS SalesName,
CU.customerNo, CU.name AS CustName, CU.postCode
FROM CarSale AS CS, Car AS C, Salesperson AS SA, Customer AS CU
WHERE CS.carNo = C.carNo AND CS.salespersonNo = SA.salespersonNo
AND CS.customerNo = CU.customerNo AND dateOfSale BETWEEN #01/09/2016#
AND #02/09/2016#
ORDER BY CS.salespersonNo;
However as you can see, this is butt-ugly! I did some research and found that I should be using "JOINS" so I went ahead and included them, this is where my problem starts.
After inserting the JOINS into the query I get something that looks like this:
SELECT CS.carNo, CS.dateOfSale, SA.salespersonNo, SA.name AS SalesName,
CU.customerNo, CU.name AS CustName, CU.postCode
FROM CarSale AS CS
JOIN Car AS C ON CS.carNo = C.carNo
JOIN Salesperson AS SA on CS.salespersonNo = SA.salespersonNo
JOIN Customer AS CU ON CS.customerNo = CU.customerNo
WHERE cs.dateOfSale BETWEEN #01/09/2016# AND #02/09/2016#
ORDER BY CS.salespersonNo;
Here are the tables:
**CarSale**
carNo salespersonNo customerNo dateOfSale
-------------------------------------------------------
**Salesperson**
salespersonNo name contactNo monthlySalary centreNo
--------------------------------------------------------------
**Customer**
customerNo name contactNo postCode
---------------------------------------------
The error I am getting is "Syntax error in FROM clause."
I think you're close, but there is something wonky about your JOINs - you have a join on 'Car', but that's not one of your tables. JOINing occurs between tables, with ON specifying the fields that are equivalent (what you are JOINing ON). With that in mind:
SELECT s.salespersonNo, s.name, c.customerNo, cs.carNo,
cs.dateofsale, c.name, c.postCode
FROM salesperson s
INNER JOIN carsale cs
ON cs.salespersonNo = s.salespersonNo
INNER JOIN customer c
ON cs.customerNo = c.customerNo
WHERE cs.dateOfSale BETWEEN #01/09/2016# AND #02/09/2016#
ORDER BY CS.salespersonNo;
Notice that your WHERE and ORDER BY are unchanged, and I just used different aliases in my test run. The main difference is in the JOIN - I join from salesperson to CarSales ON the salespersonNo, and then from CarSales to customerNo, similar to what you already have.
The syntax error is because with multiple JOINs you need parentheses around every pair of them.
It would be a lot easier to use the query designer, it does those things automatically.
SELECT CS.carNo, CS.dateOfSale, SA.salespersonNo, SA.name AS SalesName,
CU.customerNo, CU.name AS CustName, CU.postCode
FROM (((CarSale AS CS
INNER JOIN Car AS C ON CS.carNo = C.carNo)
INNER JOIN Salesperson AS SA on CS.salespersonNo = SA.salespersonNo)
INNER JOIN Customer AS CU ON CS.customerNo = CU.customerNo)
WHERE cs.dateOfSale BETWEEN #01/09/2016# AND #02/09/2016#
ORDER BY CS.salespersonNo;
As Stidgeon wrote, if these are all fields you need, you can omit the join with Car.
Related
I have two datasets
First one: Customers - Has the ID of every customer and it's attributes etc..
Second one: Comments - Has multiple comments for every customer
In the Comments table i also have the ID of the customer related to the comment, but every costumer may have multiple comments.
I want to join on the first table (Customers) the last comment that was made for them.
SELECT Customers.Name
FROM Customers LEFT JOIN
Comments
ON Customers.ID = (SELECT MAX(CommentID)
FROM Comments
WHERE Customers.ID = Comments.CustomerID
)
I'm using MAX(CommentID) to get the last comment that was added to the table.
However this throws me a syntax error, what am i doing wrong?
First get all the last comments for each customer and then join to the table:
SELECT cus.Name, com.*
FROM Customers AS cus LEFT JOIN (
SELECT * FROM Comments
WHERE CommentID IN (
SELECT MAX(CommentID)
FROM Comments
GROUP BY CustomerID
)
) AS com ON cus.ID = com.CustomerID
I think this is what you intend:
SELECT cu.Name, co.*
FROM Customers cu LEFT JOIN
Comments co
ON co.customerId = cu.ID AND
co.ID = (SELECT MAX(co2.ID)
FROM Comments co2
WHERE co.CustomerID = co2.CustomerID
);
In MS Access you probably have to write this as:
SELECT cu.Name, co.*
FROM Customers as cu LEFT JOIN
Comments as co
ON co.customerId = cu.ID AND
WHERE co.ID IS NULL OR
co.ID = (SELECT MAX(co2.ID)
FROM Comments as co2
WHERE co.CustomerID = co2.CustomerID
);
Although your query is not logically correct, I'm not sure why it would have a syntax error. One possibility is that the ids in the two tables have incompatible types. Or perhaps you are not naming the columns correctly in your query.
I am struggling with writing a select for diagram on the picture.
What I want to do is write a select, which will show me details of a car repair. As you can see in table Repairs there are only 2 attributes but I am not sure if it's necessary to add more, especialy those from employees_list and parts_list, since I want to show repair data for every vehicle by it's plate_number. By repair data I mean repair id, vehicle plate_number, all employees working on the repair and all parts used on the repair. If my diagram is wrong, please help me fix it and I have no idea how to write select for this because of the many to many relation and the use of binding tables.
This is not so hard as it may seem.
First, obviously, we have to select cars:
select vehicles.* from vehicles
then, let's join repairs:
select
vehicles.*
from vehicles
inner join repairs on vehicles.id = repairs.vehicle.id
We don't need data from repairs in resule set, so we just join it but not mention in 'select' part.
Then we have to join parts needed for repair, and info about parts itself:
select
vehicles.*
from vehicles
inner join repairs on vehicles.id = repairs.vehicle.id
inner join parts_list on parts_list.repair_id = repairs.id
inner join parts on parts_list.part_id = parts.id
For that query we get amout of rows equivalent of amount of parts needed for repair. But it would be more easy to handle such data in code if we aggregate all of them into json column. So in result set we willsee something like:
vehicle_id, vehicle_part, parts_needed_as_json
Lets aggregate this:
select
vehicles.*, json_agg(parts.*) as parts_needed
from vehicles
inner join repairs on vehicles.id = repairs.vehicle_id
inner join parts_list on parts_list.repair_id = repairs.id
inner join parts on parts_list.part_id = parts.id
group by vehicles.id, repairs.id
Now you can add same logic for employees:
select
vehicles.*,
json_agg(parts.*) as parts_needed,
json_agg(employes.*) as employees_needed
from vehicles
inner join repairs on vehicles.id = repairs.vehicle.id
inner join parts_list on parts_list.repair_id = repairs.id
inner join parts on parts_list.part_id = parts.id
inner join employees_list on employes_list.repair_id = repairs.id
inner join employees on employees_list.employee_id = employees.id
group by vehicles.id, repairs.id
BTW, I suggest you to rename your tables to lowercase and singulars.
Like: 'repair', 'employee' and 'vehicle';
Also, name your binding tables like: 'repair_part' and 'repair_employee'.
Some people even suggest to arrange related tables in that names by alphabet, like: 'employee_repair' and 'part_repair', but I think it's not required;
Maybe this is a question of taste but in most cases this leads to more readable queries.
I.e, the query above will looks like:
select
vehicle.*,
json_agg(part.*) as parts_needed,
json_agg(employee.*) as employees_needed
from vehicle
inner join repair on vehicle.id = repair.vehicle_id
inner join parts_repair on parts_repair.repair_id = repair.id
inner join part on parts_repair.part_id = part.id
inner join employees_repair on employees_repair.repair_id = repair.id
inner join employee on employees_repair.employee_id = employee.id
group by vehicle.id, repair.id
Note how elegant 'on' conditions looks now: parts_repair.part_id = part.id, parts_repair.part_id = part.id
Sorry for bad english
I am using SQL Server to query these three tables that look like (there are some extra columns but not that relevant):
Customers -> Id, Name
Addresses -> Id, Street, StreetNo, CustomerId
Sales -> AddressId, Week, Total
And I would like to get the total sales per week and customer (showing at the same time the address details). I have come up with this query
SELECT a.Name, b.Street, b.StreetNo, c.Week, SUM (c.Total) as Total
FROM Customers a
INNER JOIN Addresses b ON a.Id = b.CustomerId
INNER JOIN Sales c ON b.Id = c.AddressId
GROUP BY a.Name, c.Week, b.Street, b.StreetNo
and even if my SQL skill are close to none it looks like it's doing its job. But now I would like to be able to show 0 whenever the one customer don't have sales for a particular week (weeks are just integers). And I wonder if somehow I should get distinct values of the weeks in the Sales table, and then loop through them (not sure how)
Any help?
Thanks
Use CROSS JOIN to generate the rows for all customers and weeks. Then use LEFT JOIN to bring in the data that is available:
SELECT c.Name, a.Street, a.StreetNo, w.Week,
COALESCE(SUM(s.Total), 0) as Total
FROM Customers c CROSS JOIN
(SELECT DISTINCT s.Week FROM sales s) w LEFT JOIN
Addresses a
ON c.CustomerId = a.CustomerId LEFT JOIN
Sales s
ON s.week = w.week AND s.AddressId = a.AddressId
GROUP BY c.Name, a.Street, a.StreetNo, w.Week;
Using table aliases is good, but the aliases should be abbreviations for the table names. So, a for Addresses not Customers.
You should generate a week numbers, rather than using DISTINCT. This is better in terms of performance and reliability. Then use a LEFT JOIN on the Sales table instead of an INNER JOIN:
SELECT a.Name
,b.Street
,b.StreetNo
,weeks.[Week]
,COALESCE(SUM(c.Total),0) as Total
FROM Customers a
INNER JOIN Addresses b ON a.Id = b.CustomerId
CROSS JOIN (
-- Generate a sequence of 52 integers (13 x 4)
SELECT ROW_NUMBER() OVER (ORDER BY a.x) AS [Week]
FROM (VALUES(1),(1),(1),(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) a(x)
CROSS JOIN (SELECT x FROM (VALUES(1),(1),(1),(1)) b(x)) b
) weeks
LEFT JOIN Sales c ON b.Id = c.AddressId AND c.[Week] = weeek.[Week]
GROUP BY a.Name
,b.Street
,b.StreetNo
,weeks.[Week]
Please try the following...
SELECT Name,
Street,
StreetNo,
Week,
SUM( CASE
WHEN Total IS NULL THEN
0
ELSE
Total
END ) AS Total
FROM Customers a
JOIN Addresses b ON a.Id = b.CustomerId
RIGHT JOIN Sales c ON b.Id = c.AddressId
GROUP BY a.Name,
c.Week,
b.Street,
b.StreetNo;
I have modified your statement in three places. The first is I changed your join to Sales to a RIGHT JOIN. This will join as it would with an INNER JOIN, but it will also keep the records from the table on the right side of the JOIN that do not have a matching record or group of records on the left, placing NULL values in the resulting dataset's fields that would have come from the left of the JOIN. A LEFT JOIN works in the same way, but with any extra records in the table on the left being retained.
I have removed the word INNER from your surviving INNER JOIN. Where JOIN is not preceded by a join type, an INNER JOIN is performed. Both JOIN and INNER JOIN are considered correct, but the prevailing protocol seems to be to leave the INNER out, where the RDBMS allows it to be left out (which SQL-Server does). Which you go with is still entirely up to you - I have left it out here for illustrative purposes.
The third change is that I have added a CASE statement that tests to see if the Total field contains a NULL value, which it will if there were no sales for that Customer for that Week. If it does then SUM() would return a NULL, so the CASE statement returns a 0 instead. If Total does not contain a NULL value, then the SUM() of all values of Total for that grouping is performed.
Please note that I am assuming that Total will not have any NULL values other than from the RIGHT JOIN. Please advise me if this assumption is incorrect.
Please also note that I have assumed that either there will be no missing Weeks for a Customer in the Sales table or that you are not interested in listing them if there are. Again, please advise me if this assumption is incorrect.
If you have any questions or comments, then please feel free to post a Comment accordingly.
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
Having a bit of trouble with a basic SQL problem.
The question is that I have to find the salespersons first and last name, then their Social Insurance Number, the product description, the product price, and quantity sold where the total quantity sold is greater than 5.
I'll attach the database information below as a photo.
Product quantity sold greater than 5
SELECT ProductId
FROM ProductsSales
HAVING SUM(QuantitySold) > 5
Use that to get the rest:
SELECT s.FirstName, s.LastName, s.SIN, p.ProductDescription, ps.UnitSalesPrice, ps.QuantitySold
FROM ProductsSales ps
LEFT JOIN Products p on p.ProductID = ps.ProductID
LEFT JOIN Salesmen s on s.SalesmaneID = ps.SellerID
WHERE ps.ProductID IN
(
SELECT ProductId
FROM ProductsSales
GROUP BY ProductId
HAVING SUM(QuantitySold) > 5
)
SELECT a.FirstName, a.LastName, a.SIN, c.ProductDescription, b.UnitSalesPrice, b.QuantitySold
FROM Salesmen a
LEFT JOIN ProductsSales b
ON a.SalesmanId = b.SellerId
LEFT JOIN Products c
ON b.ProductId = c.ProductId
WHERE b.QuantitySold > 5
Select a.FirstName, a.LastName, a.SIN From Salesmen as a,
c.ProductDescriptio, c.Price, b.sum(QunatitySold)
inner join ProductSales as b on a.Salesmanid = b.sellerid
inner join Products as c on c.ProductId = b.ProductId
having b.sum(QunatitySold)> 5
group by a.FirstName, b.ProductDescription
Brad,
Welcome to SQL. Joining for me was a terrifying experience when I first started but its really easy. The general concept is this:
Pick a Join
If you want to see all records that would be common between the two table, you would use and JOIN. If you wanted to combine the two tables but still show all records you use LEFT JOIN
The basic syntax is
SELECT fieldnames FROM tablename alias
JOIN othertable alias ON firstalias.field = secondalias.field
--Example
SELECT animal, food, idtag from animals a
JOIN food f on a.animalid = f.animalid
This assumes you have a common field animalid in both the animals table and the food table. you should also ideally preface the field names with the alias to make it easier to understand like this: a.animal, f.food
And you keep going until you have joined all the tables you need.
Make sure you only request field names you want
Hope that helps