Ex No: 14 Demonstrate the Query Record Selection Operation
Aim: To demonstrate the various record selection operations using MYSQL queries.
Procedure
a) Table Creation - Create student table to store student details such as rollno, name, dob, email.
b) Table Creation - Create marks table to store student marks details such as rollno, subj1, subj2, subj3, subj4, total.
c) Insert 10 records each into student and marks table.
d) Write query to display records in student table.
e) Write query to display records in marks table.
f) Write query to display student details with marks.
g) Calculate total marks for each student using update command.
h) Write query to display student with marks less than 50 in any one subject.
i) Delete student details from database whose total is less than 200.
Query
a) Student Table Creation 
CREATE TABLE STUDENT(
 ROLLNO VARCHAR(6) PRIMARY KEY,
 NAME VARCHAR(30),
 DOB DATE,
 EMAIL VARCHAR(40) NULL);
b) Marks Table Creation 
CREATE TABLE MARKS(
 ROLLNO VARCHAR(6) NOT NULL,
 SUBJ1 INT,
 SUBJ2 INT,
 SUBJ3 INT,
 SUBJ4 INT,
 TOTAL INT);
c) Insert 10 record in each Table
Student Table 
insert into student(rollno,name,dob,email)
values('154101','Anand','2000-10-23','anand@gmail.com');
Marks Table 
insert into marks(rollno, subj1, subj2, subj3, subj4)
values('154101',65,75,85,65);
d) Query to Display Record in Student Table 
SELECT * FROM STUDENT;
e) Query to Display Record in Marks Table 
SELECT * FROM MARKS;
f) Query to Student Details with Marks 
 SELECT STUDENT.ROLLNO ROLLNO, NAME, SUBJ1, SUBJ2, SUBJ3, SUBJ4
 FROM STUDENT, MARKS
 WHERE STUDENT.ROLLNO=MARKS.ROLLNO;
g) Query to Calculate total marks for each student 
UPDATE MARKS SET TOTAL = SUBJ1+SUBJ2+SUBJ3+SUBJ4;
h) Query to Display Student Record with marks less than 50 
 SELECT STUDENT.ROLLNO, STUDENT.NAME
 FROM STUDENT, MARKS
 WHERE STUDENT.ROLLNO=MARKS.ROLLNO
 AND (SUBJ1<50 OR SUBJ2<50 OR SUBJ3<50 OR SUBJ4<50);
i) Query to Delete Student Detail with total less than 200 
 DELETE STUDENT, MARKS
 FROM STUDENT
 INNER JOIN MARKS ON STUDENT.ROLLNO = MARKS.ROLLNO
 WHERE MARKS.TOTAL<200;
Result: Thus record selection operations in database has been performed using MYSQL queries.