Please everyone share a query for all as SQL Exercises
- nested SQL statements
List each country name where the population is larger than 'Russia'.
SELECT name FROM bbc WHERE population > (SELECT population FROM bbc WHERE name='Russia')
Here is some example. A bit explanation. It select all student from student table which the studentID is matching to the courseID in which the student take the subjectID = PHY
select * from student where studentID in (select studentID from course where courseID in (select courseID from [course Details] where subjectID = PHY ) )
Please correct me if I am wrong. I also new to this.
How to select name of person, persons_id(p_id), name of orders and order_id(o_id) for those persons who order an order ?
I am sure that select is incorrect
select p_Id,FirstName,LastName,OrderName,O_Id from persons,orders where p_id=o_id
CREATE TABLE Persons ( P_Id int NOT NULL PRIMARY KEY, FirstName varchar(255), LastName varchar(255) NOT NULL, Address varchar(255), City varchar(255) ); CREATE TABLE Orders ( O_Id int NOT NULL, P_Id int, OrderName varchar(255), OrderDate varchar (255), PRIMARY KEY (O_Id), FOREIGN KEY (P_Id) REFERENCES Persons(P_Id) ); insert into persons values ('1','sara','lala','street10','de'); insert into persons values ('2','toto','no','street10','nl'); insert into persons values ('3','momo','yes','street10','ch'); insert into persons values ('4','bobo','yea','street10','sy'); insert into persons values ('5','malk','tata','street10','sy'); insert into persons values ('6','yuo','zoo','street10','UK'); insert into Orders values ('1','2','Order1','29/5/200'); insert into Orders values ('2','1','Order2','7/6/2000'); insert into Orders values ('3','2','Order3','9/9/2001'); insert into Orders values ('4','1','Order4','22/3/2002');
It is indeed incorrect:
Select P_Id, FirstName, LastName, O)Id, OrderName from Persons inner join Orders on Persons.P_Id = Orders.P_Id
You don't need a where clause, as the join will eliminate all persons without records in Orders.
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