Question

the mysql lyrics database is provided below

1.)What is a primary key used for? Can you give me an example of a primary key in the Lyrics database?

2.)What is the purpose of doing a join between two tables. Ex. Why would I ever want to join the Tracks and Titles tables together?

3.)Why is isolation important in database design?

DROP TABLES IF EXISTS Artists,Genre, Members, Titles, Tracks,SalesPeople,Studios,XrefArtistsMembers;
DROP TABLES IF EXISTS Authors,Publishers,Titles,Title_Authors,Royalties;
DROP TABLES IF EXISTS Products,Customers,Orders,Order_details;
DROP TABLES IF EXISTS Sailors,Boats,Reserves;

CREATE TABLE Artists (
   ArtistID int,
   ArtistName varchar (50) NOT NULL ,
   City varchar (25) NULL ,
   Region varchar (15) NULL ,
   Country varchar (20) NULL ,
   WebAddress varchar (40) NULL ,
   EntryDate date NULL ,
   LeadSource varchar (10) NULL
);

Insert Into Artists Values(1,'The Neurotics','Peterson','NC','USA','www.theneurotics.com','2003-05-14','Directmail');
Insert Into Artists Values(2,'Louis Holiday','Clinton','IL','USA' ,NULL,'2003-06-03','Directmail');
Insert Into Artists Values(3,'Word','Anderson','IN','USA',NULL,'2003-06-08','Email');
Insert Into Artists Values(5,'Sonata','Alexandria','VA','USA','www.classical.com/sonata','2003-06-08','Ad');
Insert Into Artists Values(10,'The Bullets','Alverez','TX','USA',NULL,'2003-08-10','Email');
Insert Into Artists Values(14,'Jose MacArthur','Santa Rosa','CA','USA','www.josemacarthur.com','2003-08-17','Ad');
Insert Into Artists Values(15,'Confused','Tybee Island','GA','USA',Null,'2003-09-14','Directmail');
Insert Into Artists Values(17,'The Kicks','New Rochelle','NY','USA',NULL,'2003-12-03','Ad');
Insert Into Artists Values(16,'Today','London','ONT','Canada','www.today.com','2003-10-07','Email');
Insert Into Artists Values(18,'21 West Elm','Alamaba','VT','USA','www.21westelm.com','2003-02-05','Ad');
Insert Into Artists Values(11,'Highlander','Columbus','OH','USA',NULL,'2002-08-10','Email');

CREATE TABLE Genre (
   Genre varchar (15)
);

Insert into Genre Values('alternative');
Insert into Genre Values('classical');
Insert into Genre Values('jazz');
Insert into Genre Values('metal');
Insert into Genre Values('R&B');
Insert into Genre Values('rap');
Insert into Genre Values('pop');

CREATE TABLE Members (
   MemberID int ,
   FirstName varchar (25) NULL ,
   LastName varchar (25) NULL ,
   Address varchar (60) NULL ,
   City varchar (25) NULL ,
   Region varchar (15) NULL ,
   PostalCode varchar (10) NULL ,
   Country varchar (20) NULL ,
   HomePhone varchar (16) NULL ,
   WorkPhone varchar (16) NULL ,
   EMail varchar (40) NULL ,
   Gender char (1) NULL ,
   Birthday date NULL ,
   SalesID smallint NULL
);

Insert Into Members Values(10,'Roberto','Alvarez','Rt 1','Anderson','IN','46019','USA','7651552983','7651628837','[email protected]','M','1968-01-18',2);
Insert Into Members Values(31,'Jose','MacArthur','51444 Vine','Santa Rosa','CA','99999','USA','6331289393',Null,'[email protected]','M','1978-06-24',1);
Insert Into Members Values(13,'Mary','Chrisman','1772 East 117th','Fishers','IN','46123','USA','3171820387',Null,'[email protected]','F','1973-03-01',1);
Insert Into Members Values(15,'Warren','Boyer','167 Alamo Dr','Alverez','TX','75601','USA','8221722883',Null,'[email protected]','M','1969-04-19',2);
Insert Into Members Values(32,'Doug','Finney','2020 Dubois','Savannah','GA','30003','USA','9821222929',Null,'[email protected]','M','1963-08-04',3);
Insert Into Members Values(19,'Terry','Irving','18a 7th St','Tybee Island','GA','30004','USA','5411252093',Null,Null,'M','1959-06-22',3);
Insert Into Members Values(21,'Michelle','Henderson','201 Bonaventure','Savannah','GA','30005','USA','8221928273',Null,Null,'F','1964-03-15',2);
Insert Into Members Values(34,'William','Morrow','PO Box 1882','New Rochelle','NY','10014','USA','9981722928',Null,'[email protected]','M','1965-03-17',2);
Insert Into Members Values(29,'Frank','Payne','5412 Clinton','New Rochelle','NY','10014','USA','9981737464',Null,Null,'M','1960-01-17',1);
Insert Into Members Values(35,'Aiden','Franks','167 East 38th','Alverez','TX','75601','USA','8321729283','8321723833','[email protected]','M','1983-09-02',2);
Insert Into Members Values(3,'Bryce','Sanders','PO Box 1292','Peterson','NC','27104','USA','6441824283',Null,'[email protected]','M','1966-06-11',2);
Insert Into Members Values(14,'Carol','Wanner','787 Airport Rd','Alverez','TX','75601','USA','6831223944',Null,Null,'F','1978-11-08',3);
Insert Into Members Values(33,'Brian','Ranier','23 Gregory Lane','London','ONT','M6Y 2Y7 ','Canada','6231842933',Null,Null,'M','1957-10-19',3);
Insert Into Members Values(7,'Marcellin','Lambert','142 Sample Rd','Alexandria','VA','20102','USA','8331929302',Null,'[email protected]','M','1959-11-14',3);
Insert Into Members Values(8,'Caroline','Kale','1515 Stone Church Rd','Allen','VA','20321','USA','7321223742',Null,Null,'F','1956-05-30',3);
Insert Into Members Values(9,'Kerry','Fernandez','15 Midway','Lynchberg','VA','21223','USA','2211229384','2211223939',Null,'M','1962-01-16',1);
Insert Into Members Values(26,'Tony','Wong','115 Maple St','McKensie','ONT','M8H 3T1','Canada','3311692832','3311692822','[email protected]','M','1955-11-01',2);
Insert Into Members Values(18,'Bonnie','Taft','RR4','Alamaba','VT','05303','USA','3721223292',Null,'[email protected]','F','1960-09-21',1);
Insert Into Members Values(20,'Louis','Holiday','15 Davis Ct','Clinton','IL','63882','USA','1451223838',Null,Null,'M','1969-07-27',2);
Insert Into Members Values(22,'Bobby','Crum','RR2','Pine','VT','05412','USA','1831828211',Null,Null,'M','1965-06-10',3);
Insert Into Members Values(28,'Vic','Cleaver','100 Maple','Reston','VT','05544','USA','8111839292',Null,Null,'M','1957-02-10',2);
Insert Into Members Values(30,'Roberto','Goe','14 Gray Rd','Columbus','OH','48110','USA','2771123943',Null,Null,'M','1967-09-12',1);
Insert Into Members Values(36,'Davis','Goodman','2020 Country Rd','Columbus','OH','48318','USA','2771152882','2771128833','[email protected]','M','1980-10-27',2);

CREATE TABLE SalesPeople (
   SalesID smallint ,
   FirstName varchar (20) NOT NULL ,
   LastName varchar (20) NOT NULL ,
   Initials varchar (3) NULL ,
   Base decimal(5,2) NULL,
   Supervisor smallint NUll
);

Insert into SalesPeople Values(1,'Bob','Bentley','bbb',100,4);
Insert into SalesPeople Values(2,'Lisa','Williams','lmw',300,4);
Insert into SalesPeople Values(3,'Clint','Sanchez','cls',100,1);
Insert into SalesPeople Values(4,'Scott','Bull','sjb',Null, Null);  

CREATE TABLE Studios (
   StudioID int,
   StudioName varchar (40) NULL ,
   Address varchar (60) NULL ,
   City varchar (25) NULL ,
   Region varchar (15) NULL ,
   PostalCode varchar (10) NULL ,
   Country varchar (20) NULL ,
   WebAddress varchar (40) NULL ,
   Contact varchar (50) NULL ,
   EMail varchar (40) NULL ,
   Phone varchar (16) NULL ,
   SalesID smallint NULL
);

Insert Into Studios Values(1,'MakeTrax','3000 S St Rd 9','Anderson','IN','46012','USA','www.maketrax.com','Gardner Roberts','[email protected]','7651223000',3);
Insert Into Studios Values(2,'Lone Star Recording','PO Box 221','Davis','TX','76382','USA','www.lsrecords.com','Manuel Austin','[email protected]','8821993748',2);
Insert Into Studios Values(3,'Pacific Rim','681 PCH','Santa Theresa','CA','99320','USA','www.pacrim.org','Harry Lee','[email protected]','3811110033',2);

CREATE TABLE Titles (
   TitleID int ,
   ArtistID int NULL ,
   Title varchar (50) NULL ,
   StudioID int NULL ,
   UPC varchar (13) NULL ,
   Genre varchar (15) NULL
);

Insert Into Titles Values(1,1,'Meet the Neurotics',1,'2727366627','alternative');
Insert Into Titles Values(3,15,'Smell the Glove',2,'1283772282','metal');
Insert Into Titles Values(4,10,'Time Flies',3,'1882344222','alternative');
Insert Into Titles Values(5,1,'Neurotic Sequel',1,'2828830202','alternative');
Insert Into Titles Values(6,5,'Sonatas',2,'3999320021','classical');
Insert Into Titles Values(7,2,'Louis at the Keys',3,'3838227111','jazz');

CREATE TABLE Tracks (
   TitleID int NOT NULL ,
   TrackNum smallint NOT NULL ,
   TrackTitle varchar (50) NULL ,
   LengthSeconds smallint NULL ,
   MP3 smallint NULL ,
   RealAud smallint NULL
);

Insert Into Tracks Values(1,1,'Hottie',233,1,1);
Insert Into Tracks Values(1,2,'Goodtime March',293,1,1);
Insert Into Tracks Values(1,3,'TV Day',305,1,1);
Insert Into Tracks Values(1,4,'Call Me an Idiot',315,1,1);
Insert Into Tracks Values(1,5,'25',402,1,1);
Insert Into Tracks Values(1,6,'Palm',322,1,1);
Insert Into Tracks Values(1,7,'Front Door',192,1,1);
Insert Into Tracks Values(1,8,'Where''s the Rain',175,1,1);
Insert Into Tracks Values(3,1,'Fat Cheeks',352,1,1);
Insert Into Tracks Values(3,2,'Rocky and Natasha',283,1,1);
Insert Into Tracks Values(3,3,'Dweeb',273,1,1);
Insert Into Tracks Values(3,4,'Funky Town',252,1,1);
Insert Into Tracks Values(3,5,'Shoes',182,1,1);
Insert Into Tracks Values(3,6,'Time In - In Time',129,1,1);
Insert Into Tracks Values(3,7,'Wooden Man',314,0,0);
Insert Into Tracks Values(3,8,'UPS',97,0,0);
Insert Into Tracks Values(3,9,'Empty',182,0,0);
Insert Into Tracks Values(3,10,'Burrito',65,0,0);
Insert Into Tracks Values(4,1,'Bob''s Dream',185,1,1);
Insert Into Tracks Values(4,2,'My Wizard',233,1,1);
Insert Into Tracks Values(4,3,'Third''s Folly',352,1,1);
Insert Into Tracks Values(4,4,'Leather',185,1,1);
Insert Into Tracks Values(4,5,'Hot Cars Cool Nights',192,1,1);
Insert Into Tracks Values(4,6,'Music in You',204,1,1);
Insert Into Tracks Values(4,7,'Don''t Care About Time',221,1,1);
Insert Into Tracks Values(4,8,'Kiss',218,1,1);
Insert Into Tracks Values(4,9,'Pizza Box',183,1,1);
Insert Into Tracks Values(4,10,'Goodbye',240,1,1);
Insert Into Tracks Values(5,1,'Song 1',285,1,1);
Insert Into Tracks Values(5,2,'Song 2',272,1,1);
Insert Into Tracks Values(5,3,'Song 3',299,1,1);
Insert Into Tracks Values(5,4,'Song 4',201,1,1);
Insert Into Tracks Values(5,5,'Song 5',198,1,0);
Insert Into Tracks Values(5,6,'Song 6',254,1,0);
Insert Into Tracks Values(5,7,'Song 7',303,1,1);
Insert Into Tracks Values(5,8,'Song 8',230,1,0);
Insert Into Tracks Values(5,9,'Song 8 and 1/2',45,1,0);
Insert Into Tracks Values(6,1,'Violin Sonata No. 1 in D Major',511,1,1);
Insert Into Tracks Values(6,2,'Violin Sonata No. 2 in A Major',438,1,1);
Insert Into Tracks Values(6,3,'Violin Sonata No. 4 in E Minor',821,1,0);
Insert Into Tracks Values(6,4,'Piano Sonata No. 1',493,1,0);
Insert Into Tracks Values(6,5,'Clarinet Sonata in E Flat',399,1,0);
Insert Into Tracks Values(7,1,'I Don''t Know',201,1,0);
Insert Into Tracks Values(7,2,'What''s the Day',332,1,0);
Insert Into Tracks Values(7,3,'Sirius',287,1,0);
Insert Into Tracks Values(7,4,'Hamburger Blues',292,1,0);
Insert Into Tracks Values(7,5,'Road Trip',314,1,0);
Insert Into Tracks Values(7,6,'Meeting You',321,1,1);
Insert Into Tracks Values(7,7,'Improv 34',441,1,1);
Insert Into Tracks Values(7,8,'Hey',288,1,1);

CREATE TABLE XrefArtistsMembers (
   MemberID int NOT NULL ,
   ArtistID int NOT NULL ,
   RespParty smallint NOT NULL
);

Insert into XrefArtistsMembers Values(20,2,1);
Insert into XrefArtistsMembers Values(31,14,1);
Insert into XrefArtistsMembers Values(3,1,1);
Insert into XrefArtistsMembers Values(10,3,1);
Insert into XrefArtistsMembers Values(13,3,0);
Insert into XrefArtistsMembers Values(7,5,1);
Insert into XrefArtistsMembers Values(8,5,0);
Insert into XrefArtistsMembers Values(9,5,0);
Insert into XrefArtistsMembers Values(32,15,0);
Insert into XrefArtistsMembers Values(19,15,1);
Insert into XrefArtistsMembers Values(21,15,0);
Insert into XrefArtistsMembers Values(34,17,1);
Insert into XrefArtistsMembers Values(29,17,0);
Insert into XrefArtistsMembers Values(15,10,1);
Insert into XrefArtistsMembers Values(35,10,0);
Insert into XrefArtistsMembers Values(14,10,0);
Insert into XrefArtistsMembers Values(33,16,1);
Insert into XrefArtistsMembers Values(26,16,0);
Insert into XrefArtistsMembers Values(18,18,1);
Insert into XrefArtistsMembers Values(28,18,0);
Insert into XrefArtistsMembers Values(22,18,0);
Insert into XrefArtistsMembers Values(30,11,1);
Insert into XrefArtistsMembers Values(36,11,0);

show tables;

Answer 1

a)Primary Key:

Explaination:

Primary key constraint is used to uniquely identify a row in a table. The key which is mentioned as primary will not be a null value as it is used to identify a row uniquely. And primary will not allow the duplicated values to insert into the table that means repeated values in the primary key column will not be allowed to use. A table can have only ONE primary key; and in the table, this primary key can consist of single or multiple columns.

From the above question, the primary keys of the lyrics data base are:

1)ArtistID from the Artist table

2)MemberID from the Members table

3)SalesID from the SalesPeople table

4)StudioID from the Studios table

5)TitleID from the Titles table

6)TitleID from the Tracks table

7)MemberID from the XrefArtistMembers table

By using the above keys we can access or identify the data in respective tables. And the condition for the above keys to become primary keys are those keys should mention as NOT NULL and UNIQUE or else as PRIMARY KEY.

b)Join: A JOIN clause is used to combine rows from two or more tables, based on a related column between them. The conditions for join are every table that we wants to join must contain the same key which should be NULL.

Explaination:

The reason that we can't join the Tracks and Titles tables together is it is not having any common key to join. And if we observe those tables, the common key is TitleID but it is mentioned NULL in the Tracks table where as not mentioned in the Titles table. So that if any value in the Titles tables will be NULL value then there is no chance for that row to make join between those rows.

c)Isolation: For every pair of transactions one should starts it's execution only after the other which already in execution will complete. This is the process of isolation. If the process of isolation will not be followed then there will be a loss of data or something else. For example:

Explaination:

There are 3 transactions A, B and C. A has total amount of $500 and it wants to send $100 to each B and C. If the both transactions will happens at a time then $100 will sent to both B and C but the amount that of A will be $400 instead of $300. There we observed the wrong transactions. If the transaction were to run in isolation then the second transaction would have read the correct balance $400 (before debiting 100$) once the first transaction went successful.

                    Hope the above is helpful. Please feel free to comment if any queries in the

                                 comment section. I will try to solve them as soon as possible.

                                            Do an up vote. Thank you...