I would need if I could help with the following code:
CREATE TABLE `car` (
`car_id` int(10) unsigned NOT NULL auto_increment,
`car_name` varchar(25) NOT NULL,
`car_year` date NOT NULL,
PRIMARY KEY (`user_id`)
) ENGINE=InnoDB;
CREATE TABLE `people` (
`peo_id` int(10) unsigned NOT NULL auto_increment,
`peo_name` varchar(50) NOT NULL,
`peo_surname` varchar(200) NOT NULL,
`car_id` int(10) unsigned NOT NULL,
PRIMARY KEY (`fav_id`),
KEY `FK_Favorites` (`user_id`),
CONSTRAINT `FK_Favorites` FOREIGN KEY (`car_id`) REFERENCES `car` (`car_id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB;
I have questions, show all cars that are more than 3 people ordered by year of car.
Thank you very much, sorry for my bad English
SELECT
c.car_id
,c.car_year
,COUNT(p.peo_id)
FROM car c
INNER JOIN people p on c.card_id = p.car_id
GROUP BY c.car_id ,c.car_year
HAVING COUNT(p.peo_id) > 3
ORDER BY c.car_year
First, find number of cars with more than three people
select car_id
from people
group by car_id
having count(*) > 3
Now, get the car details
select * from car
where car_id in
(
select car_id
from people
group by car_id
having count(*) > 3
)
order by car_year
Related
I need a list over all Books in my db.
The list should contain:
Name of the Publisher , Book Title , year of publication for all books.
The list must be sorted alphabetically in order of publisher and then title.
I am not able to sort the list for BOTH condition, just for one.
Here the tables:
Publishers table
cursor.execute("DROP TABLE IF EXISTS `Publishers`;")
cursor.execute('''
CREATE TABLE `Publishers` (
`PublisherID` INTEGER PRIMARY KEY AUTOINCREMENT,
`Name` VARCHAR(45) NULL,
`City` TEXT NULL,
`Country` TEXT NULL
);
Books table
cursor.execute("DROP TABLE IF EXISTS `Books`;")
cursor.execute('''
CREATE TABLE `Books` (
`BookID` INTEGER PRIMARY KEY AUTOINCREMENT,
`Title` VARCHAR(45) NULL,
`ISBN` VARCHAR(45) NULL,
`ISBN13` TEXT NOT NULL CHECK (length(ISBN13)=13),
`PublisherID` INT NOT NULL,
`Year_Published` VARCHAR(45) NULL,
`Price` DOUBLE NULL,
FOREIGN KEY (`PublisherID`) REFERENCES Publishers(PublisherID) ON DELETE CASCADE ON UPDATE CASCADE
);
''')
I was able to write this but not to sort it for BOTH conditions
cursor = conn.cursor()
for row in cursor.execute('''SELECT Publishers.name,title,Year_Published
FROM books
INNER JOIN publishers on publishers.PublisherID = books.PublisherID
ORDER BY
title ASC, name.publisher ASC;'''):
print(row)
cursor.close()
You seem to be looking for a join:
select p.name, b.title, b.year_published
from books b
inner join publishers p on p.publisherID = b.publisherID
order by p.name, b.title
I had written a wrong conditions. Answer seems to be the following thanks to all!1
cursor = conn.cursor()
for row in cursor.execute('''SELECT Publishers.name,title,Year_Published
FROM books
INNER JOIN publishers on publishers.PublisherID = books.PublisherID
ORDER BY
publishers.name ASC, books.title ASC;'''):
print(row)
cursor.close()
I have three tables: Category, Mail and Classification. The relationship between the tables is outlined in this SQLFiddle with some sample data: http://sqlfiddle.com/#!9/118b24/3/0
CREATE TABLE `Category` (
`id` int(6) unsigned NOT NULL,
`name` varchar(20) NOT NULL,
PRIMARY KEY (`id`)
) DEFAULT CHARSET=utf8;
CREATE TABLE `Mail` (
`id` int(6) unsigned NOT NULL,
`content` varchar(500) NOT NULL,
`date` datetime NOT NULL,
PRIMARY KEY (`id`)
) DEFAULT CHARSET=utf8;
CREATE TABLE `Classification` (
`id` int(6) unsigned NOT NULL,
`mail_id` int(6) unsigned NOT NULL,
`category_id` int(6) unsigned NOT NULL,
FOREIGN KEY (mail_id) REFERENCES Mail(id),
FOREIGN KEY (category_id) REFERENCES Category(id),
PRIMARY KEY (`id`)
) DEFAULT CHARSET=utf8;
I first run a query to get the count of emails assigned to each category:
SELECT Category.name, count(Classification.category_id) FROM Category LEFT OUTER JOIN Classification ON Classification.category_id = Category.id GROUP BY Category.name
Which works fine.
But I would now like to add a filter based on the date that is in the Email collection. If I had a join with a filter collection:
SELECT Category.name, count(Classification.category_id) FROM Category JOIN Mail ON Mail.date < '2019-03-24' LEFT OUTER JOIN Classification ON Classification.category_id = Category.id GROUP BY Category.name
But now the count only doubles and it seems the filter isn't even applied. Why isn't the filter working and what should I do to fix it?
You need a JOIN condition between Classification and Mail:
SELECT ca.name, count(cl.category_id)
FROM Category LEFT JOIN
Classification cl
ON cl.category_id = c.id LEFT JOIN
Mail m
ON m.id = cl.mail_id AND -- your JOIN key goes here
m.date < '2019-03-24'
GROUP BY c.name ;
So I have 3 tables referencing cars, assurance and accident.
I want to know the brand of vehicles who had the most accidents, compared to others.
I have tried a lot of ways to that, but mostly i only get or all the brands returned or the brand of the car that was registered the most, not the one that had most accidents
These are my tables
create table car(
n_veic bigint not null,
matric varchar(15) not null,
pais_matric text not null,
n_pess bigint not null,
tipo text not null,
cor text not null,
brand text not null,
modelo varchar(15),
primary key(n_veic),
unique(matric),
foreign key (n_pess) references pessoa(n_pess)
);
create table ensurance(
apolice bigint not null,
segurado bigint not null,
car bigint not null,
datai date not null,
dataf date not null,
cobertura numeric(10,2) not null,
primary key(apolice),
unique(segurado, veiculo),
foreign key (segurado) references pessoa(n_pess),
foreign key (car) references car(n_veic)
);
create table accident(
n_acid bigint not null,
pess_segura bigint not null,
veic_seguro bigint not null,
data date not null,
local varchar(255) not null,
descr text not null,
primary key(n_acid),
unique(n_acid, veic_seguro),
foreign key (pess_segura,veic_seguro) references ensurance(segurado, car)
This is what i tried
SELECT marca
FROM veiculo NATURAL JOIN acidente
GROUP BY marca
HAVING count (distinct n_veic)>=ALL
(SELECT count (distinct n_veic)
FROM veiculo NATURAL JOIN acidente
GROUP BY marca);
I think the logic is:
select c.marca, count(*) as num_acidentes
from acidente a join
car c
on a.veic_seguro = c.n_veic
group by c.marca
order by num_acidentes desc;
You can use fetch first 1 row only -- or whatever is appropriate for your database -- to get only one row.
Try this-
Note:
1. Try to avoid NATURAL JOIN and use specific column reference.
2. Rethink DISTINCT for count is really necessary or not.
SELECT TOP 1 marca, COUNT(DISTINCT n_veic)
FROM veiculo
NATURAL JOIN acidente
GROUP BY marca
ORDER BY COUNT(DISTINCT n_veic) DESC
So I am working on a football world cup database. These are my important tables:
CREATE TABLE Countries(
Cid SERIAL PRIMARY KEY,
Name VARCHAR(256) NOT NULL UNIQUE
);
CREATE TABLE Stadiums(
Sid SERIAL PRIMARY KEY,
Name VARCHAR(256) NOT NULL UNIQUE,
Cid INT REFERENCES Countries NOT NULL
);
CREATE TABLE Groups(
Gid SERIAL PRIMARY KEY,
Name VARCHAR(64) NOT NULL,
TYear SMALLINT REFERENCES Tournaments NOT NULL
);
CREATE TABLE Teams(
Tid SERIAL PRIMARY KEY,
Cid INT REFERENCES Countries NOT NULL,
Gid INT REFERENCES Groups NOT NULL
);
CREATE TABLE Matches(
Mid INT PRIMARY KEY,
HomeTid INT REFERENCES Teams NOT NULL,
VisitTid INT REFERENCES Teams NOT NULL,
HomeScore SMALLINT NOT NULL,
VisitScore SMALLINT NOT NULL,
MatchDate DATE NOT NULL,
MatchType VARCHAR(64) NOT NULL,
Sid INT REFERENCES Stadiums NOT NULL
);
CREATE TABLE tempmatches(
year INTEGER,
host_country VARCHAR(255),
match_id INTEGER,
type VARCHAR(255),
date DATE,
location1 VARCHAR(255),
team1 VARCHAR(255),
team2 VARCHAR(255),
score1 INTEGER,
score2 INTEGER
);
so my current problem is that I need to populate the columns HomeTid and VisitId of the Matches table with the tid's from the team's table that corresponds with the country of that team from the countries table but I'm not sure how to do that. I tried a few queries but none of them seemed to work. Has anyone an idea on how to solve this?
Using JOIN keyword you can combine 2 tables data.
Here, in this case, you have to use 3-way join.
Eg:
3-way JOIN can be used in this way:
SELECT * FROM table1 JOIN table2 ON table1.col1=table2.col2 JOIN table3 ON table3.col3=table.col1;
Here the 2 tables will get joined based on the columns mentioned after the "ON" keyword.
Here is a reference link in which JOIN is explained clearly
https://www.w3schools.com/sql/sql_join.asp
Use JOIN operation. In SQL it helps to combine several tables(queries) in one
I have some problems with a Query that I can not get out, the structure of the tables is as follows:
child
CREATE TABLE CHILD(
child_id SMALLINT,
child_name VARCHAR(255) NOT NULL,
birth_date DATE NOT NULL,
gender VARCHAR(255) NOT NULL,
address VARCHAR(255),
city VARCHAR(255),
CONSTRAINT PK_CHILD PRIMARY KEY(child_id)
letter
CREATE TABLE LETTER(
letter_id SMALLINT,
arrival_date DATE NOT NULL,
number_toys INTEGER NOT NULL,
delivery_mode VARCHAR(255) NOT NULL,
child_id SMALLINT,
CONSTRAINT PK_LETTER PRIMARY KEY(letter_id),
CONSTRAINT CHILD_FK FOREIGN KEY (child_id) REFERENCES CHILD(child_id)
);
wished_toy
CREATE TABLE WISHED_TOY(
letter_id SMALLINT,
toy_id SMALLINT,
CONSTRAINT PK_WISHED_TOY PRIMARY KEY(letter_id, toy_id),
CONSTRAINT LETTER_FK FOREIGN KEY (letter_id) REFERENCES LETTER(letter_id)
CONSTRAINT LETTER_FK FOREIGN KEY (toy_id) REFERENCES TOY(toy_id)
);
toy
CREATE TABLE TOY(
toy_id SMALLINT,
toy_name VARCHAR (255) NOT NULL,
price DECIMAL NOT NULL,
toy_type VARCHAR(255) NOT NULL,
manufacturer VARCHAR(255) NOT NULL,
CONSTRAINT PK_TOY PRIMARY KEY(toy_id),
);
I have to design a query that allows to obtain for each girl born before 2010 the
total number of toys you have ordered. The result must also include
those girls who have not written any letters. Specifically we want the
identifier of the girl, her name and city and the total number of toys ordered
(such as Total_number).
in the gender column of the child table can only be "m" of masculine or "f" of feminine
Do I have to use join?
the part that I have is this
select c.child_id,c.child_name,c.city
from letter l
join child c
on c.child_id=l.child_id
where c.gender='m' and c.birth_date between <='2010/01/01';
select c.child_id,c.child_name,c.city, coalesce( number_toys,0) counted
from
Child c
left outer join letter l
on c.child_id=l.child_id
where c.gender='m' and c.birth_date between <='2010/01/01';
Or
select c.child_id,c.child_name,c.city, count(wt.letter_id) actualToys
from
Child c
left outer join letter l
on c.child_id=l.child_id
left outer join wished_toy wt on l.letter_id=wt.letter_id
where c.gender='m' and c.birth_date between <='2010/01/01'
Group by
c.child_id,c.child_name,c.city
To count the toys referenced by database rows rather than the pre defined count