I have a little problem with one database. I have already entered data in the individual tables in the database. The problem is that with this code, it displays the column names, but didnt return rows. I can't find the error. I think the problem is in JOIN itself. Any ideas for solving the problem?
SELECT cars.brand,
cars.model,
cars.yearofproduction,
cars.engine_type,
parts.part_name,
parts.price AS MONEY,
parts.quantity
FROM CATALOG
JOIN parts
ON parts.part_name = parts.id
JOIN cars
ON CATALOG.car_id = cars.id
WHERE quantity >= '0'
HAVING MONEY < (
SELECT AVG(price)
FROM cars
);
And here the tables. I've already insert values in the tables.
CREATE TABLE CATALOG.parts
(
id INT AUTO_INCREMENT PRIMARY KEY,
part_name VARCHAR(255) NOT NULL,
price DECIMAL NOT NULL,
DESCRIPTION VARCHAR(255) DEFAULT NULL,
quantity TINYINT DEFAULT 0
);
CREATE TABLE CATALOG.cars
(
id INT AUTO_INCREMENT PRIMARY KEY,
brand VARCHAR(255) NOT NULL,
model VARCHAR(255) NOT NULL,
yearofproduction YEAR NOT NULL,
engine_type SET('Diesel', 'A95', 'Gas', 'Metan')
);
CREATE TABLE CATALOG.catalog
(
part_id INT NOT NULL,
CONSTRAINT FOREIGN KEY(part_id) REFERENCES parts(id)
ON DELETE RESTRICT ON UPDATE CASCADE,
car_id INT NOT NULL,
CONSTRAINT FOREIGN KEY(car_id) REFERENCES cars(id)
ON DELETE RESTRICT ON UPDATE CASCADE,
PRIMARY KEY(part_id, car_id)
);
Related
I'm new and I'm not so good with the triggers, I place the tables and figure out how to create this sum
-- Table `databasestreaming`.`tipologiaabbonamento`
CREATE TABLE IF NOT EXISTS `databasestreaming`.`tipologiaabbonamento` (
`idtipologiaabbonamento` INT NOT NULL AUTO_INCREMENT,
`piano abbonamento` VARCHAR(45) NULL,
`dispositivi` VARCHAR(45) NULL,
`Risoluzione` VARCHAR(45) NULL,
`Prezzo` INT NULL,
PRIMARY KEY (`idtipologiaabbonamento`))
ENGINE = InnoDB;
-- Table databasestreaming.abbonamento
CREATE TABLE IF NOT EXISTS `databasestreaming`.`abbonamento` (
`idabbonamento` INT NOT NULL AUTO_INCREMENT,
`data attivazione` DATE NULL,
`data termine` DATE NULL,
`Sport` ENUM("Si", "No") NULL,
`cliente_idcliente` INT NOT NULL,
`tipologiaabbonamento_idtipologiaabbonamento` INT NOT NULL,
`Prezzo_finale` INT NULL,
PRIMARY KEY (`idabbonamento`, `cliente_idcliente`, `tipologiaabbonamento_idtipologiaabbonamento`),
INDEX `fk_abbonamento_cliente_idx` (`cliente_idcliente` ASC) ,
INDEX `fk_abbonamento_tipologiaabbonamento1_idx` (`tipologiaabbonamento_idtipologiaabbonamento` ASC) ,
CONSTRAINT `fk_abbonamento_cliente`
FOREIGN KEY (`cliente_idcliente`)
REFERENCES `databasestreaming`.`cliente` (`idcliente`)
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `fk_abbonamento_tipologiaabbonamento1`
FOREIGN KEY (`tipologiaabbonamento_idtipologiaabbonamento`)
REFERENCES `databasestreaming`.`tipologiaabbonamento` (`idtipologiaabbonamento`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
I would like that when the user selects from enum Si with Sport, the trigger will take the price from the type of subscription (three types of subscriptions that will choose the user) and add the type of subscription chosen to the eventual or not of the sport choice, if yes, then we add +5 if instead it chooses no, in the final price I would like it to simply report the price of the chosen subscription
I am trying to create a procedure where my transfer table is joined to my account table. In my transfer table, there are two FK columns that reference the account table id column.
account table:
CREATE TABLE account (
id INT NOT NULL AUTO_INCREMENT,
name VARCHAR(30) NOT NULL,
number VARCHAR(30) NOT NULL DEFAULT '',
description VARCHAR(255)NOT NULL DEFAULT '',
is_active BIT(1) NOT NULL DEFAULT b'1',
PRIMARY KEY (id),
UNIQUE account_name (name, number)
);
transfer table:
CREATE TABLE transfer (
id INT NOT NULL AUTO_INCREMENT,
date DATE NOT NULL,
from_account INT NULL,
to_account INT NULL,
amount DECIMAL(12, 2) NOT NULL,
PRIMARY KEY (id),
FOREIGN KEY (from_account)
REFERENCES account(id),
FOREIGN KEY (to_account)
REFERENCES account(id)
);
get_account procedure:
CREATE PROCEDURE get_account()
SELECT a.*,
(SUM(t.amount) - SUM(f.amount)) AS balance
FROM account a
LEFT JOIN transfer f
ON a.id = f.from_account
LEFT JOIN transfer t
ON a.id = t.to_account
GROUP BY a.id;
I am trying to subtract the total of the from_accout column from the total of the to_account column. I am able to get the sum of just one column but when I try to get both it returns a NULL.
This seems like it should be easy, but I can't figure it out.
I'm making a database for a unit and I need a query that selects the vet with less appointments assigned so I can assign the next appointment to him or her. I don't know how to start, but I'm pretty sure I'll have to use variables here. Those are my tables:
CREATE TABLE IF NOT EXISTS staff (
stafId MEDIUMINT UNSIGNED AUTO_INCREMENT,
stafAdd VARCHAR(150) NOT NULL,
stafConNum VARCHAR(15) NOT NULL,
stafEma VARCHAR(40) NOT NULL,
stafFirNam VARCHAR(20) NOT NULL,
stafLasNam VARCHAR(30) NOT NULL,
stafPos ENUM('nurse', 'vet') NOT NULL,
PRIMARY KEY (stafId)
) engine = InnoDB;
CREATE TABLE IF NOT EXISTS vet (
vetId MEDIUMINT UNSIGNED AUTO_INCREMENT,
FOREIGN KEY (vetId) REFERENCES staff(stafId),
PRIMARY KEY (vetId)
) engine = InnoDB;
CREATE TABLE IF NOT EXISTS appointment (
appoId MEDIUMINT UNSIGNED AUTO_INCREMENT,
appoDat DATETIME NOT NULL,
appoPetId MEDIUMINT UNSIGNED,
FOREIGN KEY (appoPetId) REFERENCES pet(petId),
appoVetId MEDIUMINT UNSIGNED,
FOREIGN KEY (appoVetId) REFERENCES vet(vetId),
PRIMARY KEY (appoId)
) engine = InnoDB;
You should start by looking up the mysql MIN() function. Follow that up with learning about JOINs and you'll be breezing through this.
You could get the vet's with the number of appointment like this:
SELECT
*
FROM
(
SELECT
vet.vetId,
COUNT(*) AS nbrOfAppointment
FROM
vet
JOIN appointment
ON vet.vetId = appointment.appoVetId
) AS tbl
ORDER BY tbl.nbrOfAppointment ASC
This Request gives you the number of appointement per vet ordered by number of appointement.
Select vet.id, count(*) as nb_appointement
from vet
inner join appointement app on vet.vetId = app.appoVetId
group by vet.id
order by nb_appointement asc
I am building as type on inventory table that keeps track of stock by 6 different factors. I am using an I query much like this one:
INSERT INTO inventory ( productid, factor1, factor2, factor3, factor4, factor5, factor6, quantity, serial_number)
VALUES (242332,1,1,1,'V67',3.30,'NEW',10,NULL)
ON DUPLICATE KEY UPDATE `quantity` = VALUES(`quantity`) + quantity;
The inventory table has a UNIQUE KEY for ( productid, factor1, factor2, factor3, factor4, factor5, factor6, serial_number ). For some reason, it is not picking up on the key and just INSERTing instead of UPDATEing. Can anyone offer an explanation why? What am I missing?
Here is the table create statement:
CREATE TABLE `inventory` (
`stockid` int(11) unsigned NOT NULL AUTO_INCREMENT,
`productid` int(11) unsigned NOT NULL,
`factor1` int(11) unsigned NOT NULL,
`factor2` int(11) unsigned NOT NULL,
`factor3` int(11) unsigned NOT NULL,
`factor4` varchar(8) NOT NULL,
`factor5` decimal(10,2) NOT NULL,
`factor6` enum('A','B','C','D','NEW') NOT NULL,
`quantity` int(11) NOT NULL,
`stamp` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
`serial_number` varchar(11) DEFAULT NULL,
PRIMARY KEY (`stockid`),
UNIQUE KEY `serial_number` (`serial_number`),
UNIQUE KEY `productid_2` (`productid`,`factor1`,`factor2`,`factor3`,`factor4`,`factor5`,`factor6`,`serial_number`),
KEY `productid` (`productid`),
KEY `factor1` (`factor1`),
KEY `factor2` (`factor2`),
KEY `factor3` (`factor3`),
CONSTRAINT `books_stock_ibfk_2` FOREIGN KEY (`productid`) REFERENCES `produx_products` (`productid`),
CONSTRAINT `books_stock_ibfk_5` FOREIGN KEY (`factor1`) REFERENCES `table_factor1` (`factorid`),
CONSTRAINT `books_stock_ibfk_6` FOREIGN KEY (`factor2`) REFERENCES `table_factor2` (`factorid`),
CONSTRAINT `books_stock_ibfk_7` FOREIGN KEY (`factor3`) REFERENCES `table_factor3` (`factorid`)
)
ENGINE=InnoDB AUTO_INCREMENT=38 DEFAULT CHARSET=latin1
More in-depth:
The purpose of this table is to hold stock quantities. I think this is pretty straight forward. The factors that separate these quantities are as follows:
factor1 = storeid (the unique indentifier for the store that ownes this quantity).
factor2 = supplierid (the unique indentfier for the supplier that we got the quantity from)
factor3 = warehouseid (unique identifier for the warehouse where it resides)
factor4 = locationid (unique string for the location. Its physically painted on the shelf)
factor5 = cost (what we paid for each of the quantity)
factor6 = condition (enum ['NEW','USED','RENTAL','PREORDER']. The first three are easy, the fourth is for quantites we ordered, want to sell, but have not received it yet.)
I know this is a hefty key but I am forced to keep it this way. I have had many suggestion to move cost or condition to the product table. I cannot do this. The cost isn't always the same since we buy a lot from auctions or other places with very variable costs and conditions.
I hope this helps more to explain what I am trying to do.
Mysql allows multiple NULLs in an unique constraint.In your serial_number column replace NULL with a value and the constraint is triggered,see:
http://sqlfiddle.com/#!2/9dbd19/1
a UNIQUE index permits multiple NULL values for columns that can
contain NULL
Docs
Make the column NOT NULL and use '' which is empty.
In class, we are all 'studying' databases, and everyone is using Access. Bored with this, I am trying to do what the rest of the class is doing, but with raw SQL commands with MySQL instead of using Access.
I have managed to create databases and tables, but now how do I make a relationship between two tables?
If I have my two tables like this:
CREATE TABLE accounts(
account_id INT NOT NULL AUTO_INCREMENT,
customer_id INT( 4 ) NOT NULL ,
account_type ENUM( 'savings', 'credit' ) NOT NULL,
balance FLOAT( 9 ) NOT NULL,
PRIMARY KEY ( account_id )
)
and
CREATE TABLE customers(
customer_id INT NOT NULL AUTO_INCREMENT,
name VARCHAR(20) NOT NULL,
address VARCHAR(20) NOT NULL,
city VARCHAR(20) NOT NULL,
state VARCHAR(20) NOT NULL,
PRIMARY KEY ( customer_id )
)
How do I create a 'relationship' between the two tables? I want each account to be 'assigned' one customer_id (to indicate who owns it).
If the tables are innodb you can create it like this:
CREATE TABLE accounts(
account_id INT NOT NULL AUTO_INCREMENT,
customer_id INT( 4 ) NOT NULL ,
account_type ENUM( 'savings', 'credit' ) NOT NULL,
balance FLOAT( 9 ) NOT NULL,
PRIMARY KEY ( account_id ),
FOREIGN KEY (customer_id) REFERENCES customers(customer_id)
) ENGINE=INNODB;
You have to specify that the tables are innodb because myisam engine doesn't support foreign key. Look here for more info.
as ehogue said, put this in your CREATE TABLE
FOREIGN KEY (customer_id) REFERENCES customers(customer_id)
alternatively, if you already have the table created, use an ALTER TABLE command:
ALTER TABLE `accounts`
ADD CONSTRAINT `FK_myKey` FOREIGN KEY (`customer_id`) REFERENCES `customers` (`customer_id`) ON DELETE CASCADE ON UPDATE CASCADE;
One good way to start learning these commands is using the MySQL GUI Tools, which give you a more "visual" interface for working with your database. The real benefit to that (over Access's method), is that after designing your table via the GUI, it shows you the SQL it's going to run, and hence you can learn from that.
CREATE TABLE accounts(
account_id INT NOT NULL AUTO_INCREMENT,
customer_id INT( 4 ) NOT NULL ,
account_type ENUM( 'savings', 'credit' ) NOT NULL,
balance FLOAT( 9 ) NOT NULL,
PRIMARY KEY ( account_id )
)
and
CREATE TABLE customers(
customer_id INT NOT NULL AUTO_INCREMENT,
name VARCHAR(20) NOT NULL,
address VARCHAR(20) NOT NULL,
city VARCHAR(20) NOT NULL,
state VARCHAR(20) NOT NULL,
)
How do I create a 'relationship' between the two tables? I want each account to be 'assigned' one customer_id (to indicate who owns it).
You have to ask yourself is this a 1 to 1 relationship or a 1 out of many relationship. That is, does every account have a customer and every customer have an account. Or will there be customers without accounts. Your question implies the latter.
If you want to have a strict 1 to 1 relationship, just merge the two tables.
CREATE TABLE customers(
customer_id INT NOT NULL AUTO_INCREMENT,
name VARCHAR(20) NOT NULL,
address VARCHAR(20) NOT NULL,
city VARCHAR(20) NOT NULL,
state VARCHAR(20) NOT NULL,
account_type ENUM( 'savings', 'credit' ) NOT NULL,
balance FLOAT( 9 ) NOT NULL,
)
In the other case, the correct way to create a relationship between two tables is to create a relationship table.
CREATE TABLE customersaccounts(
customer_id INT NOT NULL,
account_id INT NOT NULL,
PRIMARY KEY (customer_id, account_id),
FOREIGN KEY customer_id references customers (customer_id) on delete cascade,
FOREIGN KEY account_id references accounts (account_id) on delete cascade
}
Then if you have a customer_id and want the account info, you join on customersaccounts and accounts:
SELECT a.*
FROM customersaccounts ca
INNER JOIN accounts a ca.account_id=a.account_id
AND ca.customer_id=mycustomerid;
Because of indexing this will be blindingly quick.
You could also create a VIEW which gives you the effect of the combined customersaccounts table while keeping them separate
CREATE VIEW customeraccounts AS
SELECT a.*, c.* FROM customersaccounts ca
INNER JOIN accounts a ON ca.account_id=a.account_id
INNER JOIN customers c ON ca.customer_id=c.customer_id;
Adding onto the comment by ehogue, you should make the size of the keys on both tables match. Rather than
customer_id INT( 4 ) NOT NULL ,
make it
customer_id INT( 10 ) NOT NULL ,
and make sure your int column in the customers table is int(10) also.
Certain MySQL engines support foreign keys. For example, InnoDB can establish constraints based on foreign keys. If you try to delete an entry in one table that has dependents in another, the delete will fail.
If you are using a table type in MySQL, such as MyISAM, that doesn't support foreign keys, you don't link the tables anywhere except your diagrams and queries.
For example, in a query you link two tables in a select statement with a join:
SELECT a, b from table1 LEFT JOIN table2 USING (common_field);
Here are a couple of resources that will help get started: http://www.anchor.com.au/hosting/support/CreatingAQuickMySQLRelationalDatabase and http://code.tutsplus.com/articles/sql-for-beginners-part-3-database-relationships--net-8561
Also as others said, use a GUI - try downloading and installing Xampp (or Wamp) which run server-software (Apache and mySQL) on your computer.
Then when you navigate to //localhost in a browser, select PHPMyAdmin to start working with a mySQL database visually. As mentioned above, used innoDB to allow you to make relationships as you requested. Makes it heaps easier to see what you're doing with the database tables. Just remember to STOP Apache and mySQL services when finished - these can open up ports which can expose you to hacking/malicious threats.
One of the rules you have to know is that the table column you want to reference to has to be with the same data type as
The referencing table . 2 if you decide to use mysql you have to use InnoDB Engine because according to your question that’s the engine which supports what you want to achieve in mysql .
Bellow is the code try it though the first people to answer this question
they 100% provided great answers and please consider them all .
CREATE TABLE accounts(
account_id INT NOT NULL AUTO_INCREMENT,
customer_id INT( 4 ) NOT NULL ,
account_type ENUM( 'savings', 'credit' ) NOT NULL,
balance FLOAT( 9 ) NOT NULL,
PRIMARY KEY (account_id)
)ENGINE=InnoDB;
CREATE TABLE customers(
customer_id INT NOT NULL AUTO_INCREMENT,
name VARCHAR(20) NOT NULL,
address VARCHAR(20) NOT NULL,
city VARCHAR(20) NOT NULL,
state VARCHAR(20) NOT NULL,
PRIMARY KEY ( account_id ),
FOREIGN KEY (customer_id) REFERENCES customers(customer_id)
)ENGINE=InnoDB;
create table departement(
dep_id int primary key auto_increment,
dep_name varchar(100) not null,
dep_descriptin text,
dep_photo varchar(100) not null,
dep_video varchar(300) not null
);
create table newsfeeds(
news_id int primary key auto_increment,
news_title varchar(200) not null,
news_description text,
news_photo varchar(300) ,
news_date varchar(30) not null,
news_video varchar(300),
news_comment varchar(200),
news_departement int foreign key(dep_id) references departement(dep_id)
);