Page 308 - IT 402 v2.0 class 10
P. 308

.  hat is  eferential Integrity   xplain its two any  purposes.           S  Sample  aper

              ns.   eferential Integrity is used to maintain accuracy and consistency of data in a relationship. In  ase  data can
                 be linked between two or more tables with the help of primary key and foreign key constraints.
                    eferential integrity helps to avoid:
                  .   ecords can be added to a related table, if there is no associated record available in the primary key
                   table.
                 2.   he values can be modified in a primary if any dependent records are present in the associated table s .
                 3.   Deleting records from a primary key table if there are any matching related records available in associated
                   table s

                  . Identify the columns and data types of a table:  irlines. Mention at least four columns with data type.
                                                                                            S  Sample  aper
             Ans.  Columns              Data type
                 Flight                 No  ext
                   No.of Passengers     Integer

                 Airlines               Text
                 Arrival  Time          Date/Time
                 Departure Time         Date/Time

                 Fares Float
                                                                                               Cr itical   T h ink ing
            B.  Application based questions:
                 .   nswer the following  uestions on the basis of following table:

                                                       Table : Student
                                    Stud_id          Stud_name         Class         Fees

                                       1          Aman                   I           3000

                                       2          Anil                               3200


                                                        Table: Teacher

                                   T_id         T_name            T_Sal           Stud_id

                                   3210      Mr.  umar           60000               1

                                   3211      Mr. Sethi           70000               2

                  i.  Identify the primary key in Student and  eacher table.
                  ii. Identify the foreign key in Teacher table.

              ns.  i.   rimary  ey in Student table : Stud id

                      rimary key in  eacher table is :   id
                  ii. Foreign key in  eacher table is : Stud id









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