SQL exists is an existing judgment

SQL exists is an existence judgment. exists is an existence judgment. If there is a result in the following query, exists is true; otherwise, it is false. drop table Student; Drop table StudentExam; Drop table Exam; create table Student (StudentID int not null primary key, Name VARCHAR (50) not null) TYPE = InnoDB; create table StudentExam (StudentID int not null, ExamID int not null, Mark INT, IfPassed SMALLINT, Comments VARCHAR (255) TYPE = InnoDB; create table Exam (ExamID INT NOT NULL PRIMARY K EY, CourseID int not null, interval int not null, SustainedOn DATE, Comments VARCHAR (255), INDEX examcourse_index (CourseID), CONSTRAINT FK_ExamCourse foreign key (CourseID) REFERENCES Course (CourseID ), INDEX examprof_index (ProfessorID), CONSTRAINT FK_ExamProf foreign key (ProfessorID) REFERENCES descriptor sor (ProfessorID) TYPE = InnoDB; insert into Student (StudentID, Name) VALUES (1, 'Joe Wang '); INSE Rt into Student (StudentID, Name) VALUES (2, 'Henry al'); insert into Student (StudentID, Name) VALUES (3, 'amma zee '); insert into Student (StudentID, Name) VALUES (4, 'Lili Lil'); insert into Student (StudentID, Name) VALUES (5, 'Sam jun '); insert into Student (StudentID, Name) VALUES (6, 'dianna Wang '); insert into Exam (ExamID, CourseID, ProfessorID, SustainedOn, Comments) VALUES (1, 1, '2017-03-12 ', 'a difficult Test that shoshould last an hour '); insert into Exam (ExamID, CourseID, ProfessorID, SustainedOn, Comments) VALUES (2003, 1, '2017-03-13 ', 'A simple two hour test '); insert into Exam (ExamID, CourseID, ProfessorID, SustainedOn, Comments) VALUES (2003, 2, '2017-03-11 ', '1 hour long'); insert into Exam (ExamID, CourseID, ProfessorID, SustainedOn) VALUES (2003, 3, '2017-03-18 '); insert into Exam (ExamID, CourseID, professorID, Sus TainedOn, Comments) VALUES (2003, 2, '1970-03-19 ', '2 hours long'); insert into Exam (ExamID, CourseID, ProfessorID, SustainedOn) VALUES, 3, '2017-03-25 '); insert into StudentExam (StudentID, ExamID, Mark, IfPassed, Comments) VALUES (2003, 'satisfactory'); insert into StudentExam (StudentID, examID, Mark, IfPassed, Comments) VALUES (, 'good result'); insert into StudentExam (StudentID, ExamID, Mark, IfPasse D, Comments) VALUES (, 'scraped pass'); insert into StudentExam (StudentID, ExamID, Mark, IfPassed, Comments) VALUES (, 39,0, 'failed, and will need to retake this one later in the year '); insert into StudentExam (StudentID, ExamID, Mark, IfPassed) VALUES (,); insert into StudentExam (StudentID, examID, Mark, IfPassed, Comments) VALUES (3,4, 78,1, 'excellent result'); insert into StudentExam (Stud EntID, ExamID, Mark, IfPassed, Comments) VALUES (3,7, 82,1, 'Great result! '); Insert into StudentExam (StudentID, ExamID, Mark, IfPassed, Comments) VALUES (4,8, 65,1, 'adequate performance'); insert into StudentExam (StudentID, ExamID, Mark, ifPassed, Comments) VALUES (, 'good result'); insert into StudentExam (StudentID, ExamID, Mark, IfPassed, Comments) VALUES, 'Below exists'); insert into StudentExam (StudentID, ExamID, Mark, IfPassed, Comments) VALUES (5, 1, 26, 0, 'Very poor performance. recommend this student drop this module '); insert into StudentExam (StudentID, ExamID, Mark, IfPassed, Comments) VALUES (, 'good result '); insert into StudentExam (StudentID, ExamID, Mark, IfPassed, Comments) VALUES (5, 2, 62,1, 'good result'); insert into StudentExam (StudentID, ExamID, Mark, IfPassed, Comments) VALUES (6, 3, 'excellent work'); insert into StudentExam (StudentID, ExamID, Mark, IfPassed) VALUES (6, 6, 69, 1); insert into StudentExam (StudentID, ExamID, mark, IfPassed, Comments) VALUES (6,10, 58,1, 'adequate performance '); SELECT StudentID, Name FROM Student sWHERE EXISTS (SELECT StudentID FROM StudentExam e WHERE Mark <40 AND e. studentID = s. studentID );