Lecture12.txt

Lecture-12:
Delete Statement in SQL:

Update: It is used to delete record from database or table but never effect the structure of table.
Example: Amazon => Database => Customer
                SlNo              Name                     Address                         Age
                   1.             Rupu                     Agarpara                         22
                   2.             Rup                 Salt Lake, Sector-2                   20
                   3.             Rupayan                    Fulia                          24
                   4.             Rupi                      Newtown                         21
Syntax: delete from table_name 
               where column_name= ”condition”;
Command: delete Customer where SlNo= 2;
Output:
                SlNo              Name                     Address                         Age
                   1.             Rupu                     Agarpara                         22
                   3.             Rupayan                    Fulia                          24
                   4.             Rupi                      Newtown                         21

Important Points:
1.	Always use where clause with update statement.
2.	Risky Command.
Interview Questions:
1.	What will delete command do to table/database?
Ans> Delete command is used to delete records from table. It is using where clause deletes the particular row/data from the table otherwise all data are deleted from the database, that’s why delete is a very risky command. But delete command never effects the database structure.
2.	Difference between Delete and Drop command.
3.	Difference between Delete and Drop and Truncate.