see a quell, Sql Server

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--Sql Server 2014 Express Edition
--Batches are separated by 'go'

CREATE TABLE Students (
    Roll_no int  PRIMARY KEY ,
    Student_name varchar(255),
    );
 CREATE TABLE Performance (
    Roll_no int,
    Subject_code char,
    Marks int,
   PRIMARY KEY  (Roll_no,Subject_code )
                           );
 INSERT INTO Students
 VALUES 
      ('1','Amit'),
      ('2','Priya'),
      ('3','Vinit'),
      ('4','Rohan'),
      ('5','Samita');
 INSERT INTO Performance
 VALUES
      ('1','A','86'),
      ('1','B','95'),
      ('1','C','90'),
      ('2','A','89'),
      ('2','C','92'),
      ('3','C','80');
      Select * from Students
      Select * from Performance
     
      /* Select sum of marks returning with Student names in a new table from table Performance*/
      Select Students.Student_name,sum(Performance.Marks) as SumofMarks from 
      Students join Performance
      on Students.Roll_no = Performance.Roll_no
      Group by Students.Student_name
      
      Select sum(P.Marks) as Sumofmarks,S.Student_name
      from Students as S, Performance as P
      Where P.MarKs > 84
      Group by Student_name
      
      Select Sum(Performance.MArks) as SumofallMArks from Performance

View schema
Execution time: 0,03 sec, rows selected: 20, rows affected: 11, absolute service time: 0,22 sec, absolute service time: 0,22 sec