Page 179 - TrackpadV5.1_class8
P. 179

SELECT Marks FROM Student WHERE FirstName like 'D%';                            +-------+
                                                                                                     | Marks |
                                                                                                     +-------+
                                                                                                     |   480 |
                 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    |   475 |
                                      +-----------+-----------+----------+-------+

                 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;















                                                                                               Techipedia (MySQL)  177
   174   175   176   177   178   179   180   181   182   183   184