I am having trouble to answer this question :
Display the last name and client company (COMPANY) for the employees who made a sale for clients of Paris" sorted on the Company Name.
Here is my code :
select NAME from EMPLOYEES inner join SALES on EMPLOYEES.NO_EMPLOYEES = SALE.NO_EMPLOYEES
union
select COMPANY from SALES inner join CLIENTS on SALES.CODE_CLIENT = CLIENTS.CODE_CLIENT where CLIENTS.CITY = 'Paris'
Problem is that union gives me only one column... How to solve this issue ?
Thanks for your help !
I think you just want two joins:
select e.NAME, c.COMPANY
from EMPLOYEES e join
SALES s
on e.NO_EMPLOYEES = s.NO_EMPLOYEES join
CLIENTS c
on s.CODE_CLIENT = c.CODE_CLIENT
where c.CITY = 'Paris';
Related
I have two MySQL-tables:
Persons (pid,name,companyID,companyName)
Orders (oid,companyID,details)
Now I want to count the number of order_id for each companyName as following:
Name Total
-------------------
CompanyName1 : 1200
CompanyName2 : 758
CompanyName3 : 11
I used this query but it's not working properly.
SELECT count(o.oid) as total,p.companyName
FROM orders as o, persons as p
WHERE o.companyID = p.companyID
GROUP BY p.companyName
Use join and group the result by p.companyID
SELECT p.companyName, count(o.oid) as total
FROM orders as o join persons as p
on o.companyID = p.companyID
GROUP BY p.companyID
If you are missing the companies without any orders you can use a left join.
SELECT p.companyName, count(*) as total
FROM persons p
LEFT JOIN orders o ON o.companyID = p.companyID
GROUP BY p.companyID, p.companyName
Please do not use the old, legacy join syntax any more - it is outdated since 1992.
Your data model looks messed up. That you have company ids and names in the person table but no corresponding companies table is highly suspicious.
In any case, presumably there can be multiple rows per company. You can condense the persons table and then join:
SELECT c.companyName, COUNT(*) as total
FROM orders o JOIN
(SELECT DISTINCT companyId, companyName
FROM persons p
) c
ON o.companyID = c.companyID
GROUP BY c.companyName;
However, you should fix the data model so you have a real bona fide companies table -- especially because you seem to care about that entity.
I have 3 tables in my database
companies{
id,
name,
address
}
stores{
id,
name,
address,
company_id
}
invoices{
id,
total,
date_time,
store_id
}
As you can see, each store is connected to a company via foreign key, also each invoice is connected to a store.
My question is, how can i write a SQL query which will return all stores by a company and order them by their turnover?
If i use the query:
SELECT s.*,
sum(i.total) as turnover FROM store s
JOIN invoices i
ON i.store_id = s.id
WHERE YEAR(i.date_time) = 2019;
I can see the turnover for one store for a year 2019 for example, but i'm struggling to find a way to get a list of store ordered by their turnover for a certain period.
You're going to need to join all 3 tables:
SELECT *
FROM
companies c
INNER JOIN stores s on s.company_id = c.id
INNER JOIN invoices i ON i.store_id = s.id
That's your entire raw data in detailed list. Then you say you want it for a certain company only:
SELECT *
FROM
companies c
INNER JOIN stores s on s.company_id = c.id
INNER JOIN invoices i ON i.store_id = s.id
WHERE c.name = 'Acme Rubber Co'
Then you only want the stores and the invoices amounts:
SELECT s.name, i.total
FROM
companies c
INNER JOIN stores s on s.company_id = c.id
INNER JOIN invoices i ON i.store_id = s.id
WHERE c.name = 'Acme Rubber Co'
Then you want a row set where each line is a single store and the sum of all invoices for that store:
SELECT s.name, SUM(i.total)
FROM
companies c
INNER JOIN stores s on s.company_id = c.id
INNER JOIN invoices i ON i.store_id = s.id
WHERE c.name = 'Acme Rubber Co'
GROUP BY s.name
Lastly you want them in descending order, highest total first:
SELECT s.name as storename, SUM(i.total) as turnover
FROM
companies c
INNER JOIN stores s on s.company_id = c.id
INNER JOIN invoices i ON i.store_id = s.id
WHERE c.name = 'Acme Rubber Co'
GROUP BY s.name
ORDER BY turnover DESC
The order of evaluation in sql is FROM(with joins), WHERE, GROUP BY, SELECT, ORDER BY which is why I use different names in eg the order by than I do in the group by. Conceptually your db only sees the names of things as output by the immediately previous operation. Mysql isn't actually too picky but some db are - you couldn't say GROUP BY storename in sql server because the SELECT that creates the storename alias hasn't been run at the time the group by is done
Note: I wasn't really sure on what you were looking for in a WHERE - you started by saying "all stores turnover for a certain company" and finished saying you were "struggling to get turnover for a period"
If you want a period, use eg WHERE somedatecolumn BETWEEN '2000-01-01' AND '2000-12-31' (Between is inclusive) or WHERE somedatecolumn >= '2000-01-01' AND somedatecolumn < '2001-01-01' (A good pattern to use if the date includes a time too). It is almost never wise to call a function on a column you're searching with, ie do not do WHERE YEAR(somedatecolumn) = 2000 because it disables indexing on the column and makes the search very slow
This is my query:
SELECT count(*) as total, dp.name,dp.id,dp.description, dp.avatar
FROM `doctors` d
right join departments dp on d.department_id = dp.id
group by d.department_id
I have to tables: doctors and departments. I want to extract the total number of doctors from each department. This query works fine, it returns me all of the deparments, which have a doctors, but not which does not have. Somehow I want to show all of the departements and a total, which represents the doctors whose belong to a department. How can i do that ?
This is the doctor table:
and this is the departments table
You can give this a try:
SELECT
(SELECT count(*) FROM doctors d WHERE d.department_id = dp.id) AS total,
dp.*
FROM departments AS dp
And if you want to use JOIN then try this:
SELECT
COUNT(d.department_id) AS total,
dp.*
FROM departments AS dp
LEFT JOIN doctors AS d ON dp.id = d.department_id
GROUP BY dp.id
SELECT (SELECT count(*) FROM doctors AS d WHERE d.id = dp.id) as total, dp.name,dp.id,dp.description, dp.avatar
FROM departments dp
there are multiple ways of doing this ofcourse, I would do it like this
i dont think you need to join you just need a count of all the doctors and you dont do anything with the rest of the information
In my couple of decades working with SQL I've never used right joins. I've always found the LEFT join easier to read. I also try and return the columns in order of the highest to lowest level of detail and finish with sum's and counts. It reads a lot better.
Try this:
SELECT dp.id,dp.name,dp.description, dp.avatar,count(*) as total
FROM departments dp
LEFT JOIN doctors d
on d.department_id = dp.id
GROUP BY dp.id,dp.name,dp.description, dp.avatar
You must always group by every column within your select clause except those that are an aggregation (e.g. sum,count) or a constant.
i am having problems using an inner join for 3 tables..
i need to display cust_id, the customer forename and surname, the product name<-(from products table) and date of sale<--(from sales table), also i need to display in order of the most recent dates first.
this is what i have got so far
enter SELECT
customers.cust_id,
customers.forename,
customers.surname,
products.prod_name,
sales.Date_of_sale
FROM
customers
INNER JOIN
sales
ON
customers.cust_id = sales.cust_id; here
id really appreciate it if you could help me here, thank you..
Just add one more JOIN to the products table and include an ORDER BY clause:
SELECT
c.cust_id,
c.forename,
c.surname,
p.prod_name,
s.Date_of_sale
FROM customers c
INNER JOIN sales s ON c.cust_id = s.cust_id
INNER JOIN products p ON s.product_id = p.product_id
ORDER BY s.Date_of_sale DESC
A Visual Explanation of SQL Joins
I think the problem is in your FROM parameter.
You specified only customer.
SELECT customers.cust_id, customers.forename, customers.surname, products.prod_name, sales.Date_of_sale
FROM
customers , products , sales
INNER JOIN
sales
ON
customers.cust_id = sales.cust_id;
I want to see what customers ordered what from a given manufacture.
I have theses tables (with columns):
items (item_num, order_num, stock_num, manu_code, quantity, etc.)
stock (stock_num, manu_code, description, unit_price, etc.)
orders (order_num, order_date, customer_num, ship_instruct, etc.)
customer (customer_num, fname, lname, company, address1, etc.)
This is my query right now, but I believe it is returning a cross product of some sort:
SELECT concat(c.fname," ", c.lname) AS fullname, s.description
FROM items i, stock s, customer c JOIN orders o
ON o.customer_num=c.customer_num
WHERE o.order_num=i.order_num AND i.manu_code = 'ANZ';
Which returns a big list (1000 lines) with lots of duplicate entires,
Anthony Higgens | baseball gloves
Anthony Higgens | baseball gloves
. .
. .
. .
Kim Satifer | running shoes
What am I doing wrong?
FROM items i, stock s, customer c does a cartesian join of those three tables involved, but your WHERE does very little restriction on that cartesian join.
If you do some more explicit joining you will grealy cut down on duplicates and more properly express what you are trying to do. Use INNER JOINS and the correct join criteria instead of just listing all the tables after the FROM. Example: (there are more such criteria, you would need to apply to the JOINS, but this is one example): INNER JOIN stock ON stack.manu_code = items.manu_code.
Finally, you can use SELECT DISTINCT or GROUP BY to further reduce duplicates. But if you get your explicit JOINs with JOIN criteria right, you should not have too many duplicates.
Try this:
SELECT DISTINCT concat(c.fname," ", c.lname) AS fullname, s.description
FROM customer c
INNER JOIN orders o ON c.customer_num = o.customer_num
INNER JOIN items i ON o.order_num = i.order_num
INNER JOIN stock s on s.stock_num = i.stock_num
WHERE i.manu_code = 'ANZ'
This should work :
SELECT concat(a.fname, " ", a.lname ) as name
, d.description as desc
FROM CUSTOMER a
INNER JOIN ORDERS b
on a.customer_num = b.customer_num
INNER JOIN ITEMS c
on b.order_num = c.order_num
INNER JOIN STOCK d
on c.manu_code = d.manu_code
where c.manu_code like 'ANZ'
group by name,desc
Thanks everybody, I think this is working now:
SELECT DISTINCT concat(c.fname," ", c.lname) AS fullname, s.description
FROM customer c
INNER JOIN orders o ON c.customer_num = o.customer_num
INNER JOIN items i ON o.order_num = i.order_num
INNER JOIN stock s on s.stock_num = i.stock_num
WHERE i.manu_code = 'ANZ';