Page 146 - TP_Play_V2.2_Class8
P. 146

+-----------+-------+
                                                    | FirstName | Marks |
                                                    +-----------+-------+
                                                    | Divya     |   450 |
                                                    | Aadarsh   |   450 |
                                                    +-----------+-------+
                    SELECT Marks FROM Student WHERE FirstName like 'D%';

                                                            +-------+
                                                            | Marks |
                                                            +-------+
                                                            |   450 |
                                                            +-------+
              UPDATING RECORDS IN A TABLE

              Sometime, you may need to change the details inserted into a table. In that case, the UPDATE command
              will work. The syntax of the UPDATE command is:

                  UPDATE table_name SET field_change=value WHERE field_criteria=value;
              Let us change the marks of the student  having  10002  as StudentID  from 480  to 485  by using  the
              following command:

                  UPDATE Student SET Marks = 485 where StudentID = 10002;
                                      +-----------+-----------+----------+-------+
                                      | StudentID | FirstName | LastName | Marks |
                                      +-----------+-----------+----------+-------+
                                      |     10001 | Amit      | Sharma   |   450 |
                                      |     10002 |  Divya    | Kaushik  |   485 |
                                      |     10003 |  Aadarsh  | Kumar    |   450 |
                                      +-----------+-----------+----------+-------+

              REMOVING RECORDS FROM A TABLE

              The DELETE command is used to remove records from a table. The DELETE command can be used in
              two ways:
                  Without WHERE clause       With the WHERE clause

              We can remove a specific record by using the WHERE clause with the DELETE command. If we use the
              DELETE command without the WHERE clause, it will remove all the records from a table. Let us use the
              DELETE command to remove the record of a student whose LastName is Kumar:

                  DELETE FROM Student WHERE LastName="Kumar";
              To remove all the records, following command is used:

                  DELETE FROM Student;
              DROP command is used to delete the structure of a table or even the database.
              Example:

              To delete the table Student from database:
                  DROP TABLE student;


                  To delete the database School:
                  DROP DATABASE school;




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