Consider the tables given below while attempting the following questions:
Train
Reservation
(i) Identify the primary key column of Train and Reservation.
(ii) Help Mr. Sajal in identifying the wrong statement with reference to UNION clause:
a. Each SELECT statement within UNION must have the same number of columns
b. The columns must also have similar data types
c. The columns in each SELECT statement must also be in the same order
d. By default, the UNION operator selects all the values.
