I need to write SQL query like:
Show all countries with more than 1000 users, sorted by user count.
The country with the most users should be at the top.
I have tables:
● Table users (id, email, citizenship_country_id)
● Table countries (id, name, iso)
Users with columns: id, email, citizenship_country_id
Countries with columns: id, name, iso
SELECT countries.name,
Count(users.citiizenship_country_id) AS W1
FROM countries
LEFT JOIN users ON countries.id = users.citizenship_country_id
GROUP BY users.citiizenship_country_id, countries.name
HAVING ((([users].[citiizenship_country_id])>2));
But this does not work - I get an empty result set.
Could you please tell me what I'm doing wrong?
A LEFT JOIN is superfluous for this purpose. To have 1000 users, you need at least one match:
SELECT c.name, Count(*) AS W1
FROM countries c JOIN
users u
ON c.id = u.citizenship_country_id
GROUP BY c.name
HAVING COUNT(*) > 1000;
Notice that table aliases also make the query easier to write and to read.
Group by country name and use HAVING Count(u.citiizenship_country_id)>1000, it filters rows after aggregation:
SELECT c.name,
Count(u.citiizenship_country_id) AS W1
FROM countries c
INNER JOIN users u ON c.id = u.citizenship_country_id
GROUP BY c.name
HAVING Count(u.citiizenship_country_id)>1000
ORDER BY W1 desc --Order top counts first
;
As #GordonLinoff pointed, you can use INNER JOIN instead of LEFT JOIN, because anyway this query does not return counries without users and INNER JOIN performs better because no need to pass not joined records to the aggregation.
Related
I have a table here in which I want to write a SELECT query in SQL Server that allows me to get the following:
For each unique combination of SalesPerson x Country, get only the rows with the latest Upload_DateTime
However, I am trying to do a group-by and inner join, but to no avail. My code is something like this:
SELECT t1.[SalesPerson], t1.[Country], MAX(t1.[Upload_DateTime]) as [Upload_DateTime]
FROM [dbo].[CommentTable] AS t1
GROUP BY t1.[SalesPerson], t1.[Country]
INNER JOIN SELECT * FROM [dbo].[CommentTable] as t2 ON t1.[SalesPerson] = t2.[SalesPerson], t1.[Country] = t2.[Country]
It seems like the GROUP BY needs to be done outside of the INNER JOIN? How does that work? I get an error when I run the query and it seems my SQL is not right.
Basically, this subquery will fetch the person, the country and the latest date:
SELECT
SalesPerson, Country, MAX(uplodaed_datetime)
FROM CommentTable
GROUP BY SalesPerson, Country;
This can be used on a lot of ways (for example with JOIN or with an IN clause).
The main query will add the remaing columns to the result.
Since you tried a JOIN, here the JOIN option:
SELECT
c.id, c.SalesPerson, c.Country,
c.Comment, c.uplodaed_datetime
FROM
CommentTable AS c
INNER JOIN
(SELECT
SalesPerson, Country,
MAX(uplodaed_datetime) AS uplodaed_datetime
FROM CommentTable
GROUP BY SalesPerson, Country) AS sub
ON c.SalesPerson = sub.SalesPerson
AND c.Country = sub.Country
AND c.uplodaed_datetime = sub.uplodaed_datetime
ORDER BY c.id;
Try out: db<>fiddle
I am trying to select which co-ordinates from OA table are NOT found in the CUSTOMER address table.
SELECT DISTINCT
OA.CO_ORDS
FROM
CUSTOMER
INNER JOIN
OA ON customer.address=oa.co_ords
ORDER BY ID ASC;
Returns the co-ordinates which ARE in the customer table. How do I return those that are not in the customer table?
Am I also able to COUNT how many of customers are is in each co-ordinate (The co-ords are not specific and not accurate, this is purely for query testing only)
SELECT DISTINCT
OA.CO_ORDS
FROM
CUSTOMER
INNER JOIN
OA ON customer.address=oa.co_ords
ORDER BY ID ASC;
We can use NOT EXISTS to find those co-ordinates which don't appear in the customer table:
SELECT co_ords
FROM oa
WHERE
NOT EXISTS
(SELECT 1 FROM customers
WHERE address = oa.co_ords)
ORDER BY id;
In order to count how many customers belong to a certain co-ordinate, we can use COUNT with GROUP BY, something like this:
SELECT c.address, COUNT(*)
FROM customers c
JOIN oa
ON c.address = oa.co_ords
GROUP BY c.address;
It could be better to count a specific column instead of *.
It could also be better to use an IN clause instead of JOIN the tables:
SELECT c.address, COUNT(*)
FROM customers c
WHERE address IN
(SELECT co_ords FROM oa)
GROUP BY c.address;
Such details depend on your exact table structure, you should please try this out or provide more details.
You could also do:
SELECT co_ords
FROM oa
MINUS
SELECT address
FROM customers;
which can sometimes be faster than doing an anti-join. Note that MINUS does a distinct on the resultset.
Soo i need to make a consult that shows the id of the city, name, and how much clients that city have including cities that have 0 clients;
I was first trying to just get the cities that have clients but have no ideia on how to include cities that have no clients.
I have a table: CITIES that cointains ID_city, NAME, and REGION
and the table: CLIENTS that cointains ID_client, NAME and ID_city
query:
select l.name, l.ID_city, count(c.name) from clients c
JOIN cities l on l.ID_city = c.ID_city
GROUP BY l.name, l.ID_city;
use left join
select l.nomecidade, l.codcidade, count(c.nomecliente) from prova.clientes c
left JOIN prova.cidades l on l.codcidade = c.codcidade
GROUP BY l.nomecidade, l.codcidade
Use left join but make sure which table you considering first.
The code below should solve the problem:
select C1.name, C1.ID_city, count(C2.name) from cities C1
LEFT JOIN clients C2 on C1.ID_city = C2.ID_city
GROUP BY C1.name, C1.ID_city;
SELECT f_name,l_name,teachers.first_name,teachers.t_id,p_id,paid_amount,family_id,date,sum(payments.paid_amount)
FROM payments
LEFT JOIN family ON family.id = payments.family_id
LEFT JOIN teachers ON family.teacher_id = teachers.t_id
How can I get the selected columns fully and the sum column separately?
because that sum function makes all the selected result one row
SELECT f_name,l_name,teachers.first_name,teachers.t_id,p_id,paid_amount,family_id,date
FROM payments
LEFT JOIN family ON family.id = payments.family_id
LEFT JOIN teachers ON family.teacher_id = teachers.t_id
This query is working fine without the sum column
You didn't tell the database, which column to use for aggregating the data. Don't know which database you are using, but some complain, that there is no GROUP BY statement in the SQL text.
Please try with the following query:
SELECT f_name,l_name,teachers.first_name,teachers.t_id,p_id,paid_amount,family_id,date,sum(payments.paid_amount)
FROM payments
LEFT JOIN family ON family.id = payments.family_id
LEFT JOIN teachers ON family.teacher_id = teachers.t_id
GROUP BY f_name,l_name,teachers.first_name,teachers.t_id,p_id,paid_amount,family_id,date
GROUP BY tells the database, which are the key columns in the aggregation.
If you want all the payments, use a subquery or join:
SELECT f_name, l_name, t.first_name, t.t_id, p.p_id, p.paid_amount, p.family_id, date,
(select sum(p.paid_amount) from payments) as all_paid
FROM payments p LEFT JOIN
family f
ON f.id = p.family_id LEFT JOIN
teachers t
ON f.teacher_id = tetchers.t_id;
SELECT f_name,l_name,t.first_name,t.t_id,p_id,paid_amount,family_id,date,sum(p.paid_amount)
FROM payments p,family f,teachers t where f.id = p.family_id and f.teacher_id = t.t_id
Group by f_name,l_name,teachers.first_name,teachers.t_id,p_id,paid_amount,family_id
You can add date column also in Group by expression based on your requirement. Example:
f_name,l_name,teachers.first_name,teachers.t_id,p_id,paid_amount,family_id,date
I'm having problems getting an accurate count of a column after joining others. When a column is joined I would still like to have a DISTINCT count of the table that it is being joined on.
A restaurant has multiple meals, meals have multiple food groups, food groups have multiple ingredients.
Through the restaurants id I want to be able to calculate how many of meals, food groups, and ingrediants the restaurant has.
When I join the food_groups the count for meals increases as well (I understand this is natural behavior I just don't understand how to get what I need due to it.) I have tried DISTINCT and other things I have found, but nothing seems to do the trick. I would like to keep this to one query rather than splitting it up into multiple ones.
SELECT
COUNT(meals.id) AS countMeals,
COUNT(food_groups.id) AS countGroups,
COUNT(ingrediants.id) AS countIngrediants
FROM
restaurants
INNER JOIN
meals ON restaurants.id = meals.restaurant_id
INNER JOIN
food_groups ON meals.id = food_groups.meal_id
INNER JOIN
ingrediants ON food_groups.id = ingrediants.food_group_id
WHERE
restaurants.id='43'
GROUP BY
restaurants.id
Thanks!
The DISTINCT goes inside the count
SELECT
COUNT(DISTINCT meals.id) AS countMeals,
COUNT(DISTINCT food_groups.id) AS countGroups,
COUNT(DISTINCT ingrediants.id) AS countIngrediants
FROM
restaurants
INNER JOIN
meals ON restaurants.id = meals.restaurant_id
INNER JOIN
food_groups ON meals.id = food_groups.meal_id
INNER JOIN
ingrediants ON food_groups.id = ingrediants.food_group_id
WHERE
restaurants.id='43'
GROUP BY
restaurants.id
You're going to have to do subqueries, I think. Something like:
SELECT
(SELECT COUNT(1) FROM meals m WHERE m.restaurant_id = r.id) AS countMeals,
(SELECT COUNT(1) FROM food_groups fg WHERE fg.meal_id = m.id) AS countGroups,
(SELECT COUNT(1) FROM ingrediants i WHERE i.food_group_id = fg.id) AS countGroups
FROM restaurants r
Where were you putting your DISTINCT and on which columns? When using COUNT() you need to do the distinct inside the parentheses and you need to do it over a single column that is distinct for what you're trying to count. For example:
SELECT
COUNT(DISTINCT M.id) AS count_meals,
COUNT(DISTINCT FG.id) AS count_food_groups,
COUNT(DISTINCT I.id) AS count_ingredients
FROM
Restaurants R
INNER JOIN Meals M ON M.restaurant_id = R.id
INNER JOIN Food_Groups FG ON FG.meal_id = M.id
INNER JOIN Ingredients I ON I.food_group_id = FG.id
WHERE
R.id='43'
Since you're selecting for a single restaurant, you shouldn't need the GROUP BY. Also, unless this is in a non-English language, I think you misspelled ingredients.