create table Author(
    author_id Int Primary Key Auto_Increment ,
    author_name Varchar(50) Not Null
);
create table Books(
    book_id Int  NOT Null AUTO_INCREMENT PRIMARY KEY ,
    title Varchar(30) NOT NULL,
    ratings Decimal(5,2),
    au_id int,
     
    Foreign Key (au_id) references Author(author_id)
);
insert into Author (author_name) values ('Raj') ,('Ram'), ('Shyam'), ('Mohan') ,('Sumit');
INSERT INTO Books(title, ratings, au_id) VALUES ('She Know to Dance', 1.2, 1),('He Willing to Dance', 4.2, 2),('Y Y Dance', 3.4, 2),('Come and Dance', 2.67, 4),('Not Now Never', 5.00, 3);

#select author_name , title, ratings from Author INNER JOIN Books On Books.au_id = Author.author_id;

#select author_name,title,ratings from Author Left Join Books On Books.au_id = Author.author_id ;

#select author_name,ifNull(title,'Not FOund'),IfNull(ratings,0) from Author Left Join Books On Books.au_id = Author.author_id ;

select author_name ,ratings, CASE WHEN IFNULL(ratings,0) >= 3 then "GOOD" ELSE "AVERAGE" END as REMARK  from Author INNER JOIN Books On Books.au_id = Author.author_id;
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