Alter the CUSTOMERS table to change the primary key from CustomerID to Email for better identification of customers.Alter the RESERVATIONS table to allow ReservationTime to be nullable in case some reservations do not have a specific time set.
Question
Alter the CUSTOMERS table to change the primary key from CustomerID to Email for better identification of customers.Alter the RESERVATIONS table to allow ReservationTime to be nullable in case some reservations do not have a specific time set.
Solution
To alter the CUSTOMERS table to change the primary key from CustomerID to Email, you would use the following SQL commands:
Step 1: First, you need to drop the existing primary key. Here is the SQL command for that:
ALTER TABLE CUSTOMERS
DROP PRIMARY KEY;
Step 2: Then, you can set the Email as the new primary key. Here is the SQL command for that:
ALTER TABLE CUSTOMERS
ADD PRIMARY KEY (Email);
To alter the RESERVATIONS table to allow ReservationTime to be nullable, you would use the following SQL command:
ALTER TABLE RESERVATIONS
MODIFY ReservationTime TIME NULL;
This command changes the ReservationTime column to allow NULL values, which means that it's not necessary to have a specific time set for a reservation.
Similar Questions
Alter the CUSTOMERS table to change the primary key to Email to ensure each customer is uniquely identified by their email address.Drop the primary key from the BOOKINGS table as it is no longer required.
Alter the CUSTOMERS table to change the primary key to Email to ensure each customer is uniquely identified by their email address.
Alter the RESERVATIONS table to allow ReservationTime to be nullable in case some reservations do not have a specific time set.
Charles is developing a travel booking system to manage customers, bookings, and payments. The system needs to handle three main types of data: CUSTOMERS, BOOKINGS, and PAYMENTS. To perform this the user needs to create the following tables with the mentioned constraints: symbol refers to the primary key NN refers to Not NULL After creating the tables, Charles needs to:Alter the CUSTOMERS table to change the primary key to Email to ensure each customer is uniquely identified by their email address.Drop the primary key from the BOOKINGS table as it is no longer required.Note: The user must write only the query to create, alter, and drop the table. The query to display the description of the table is already given.Input format :No console inputOutput format :The output displays the successful table creation status and the structure of all three tablesRefer to the sample output.Sample test cases :Input 1 :Output 1 :Table CUSTOMERS created.Table BOOKINGS created.Table PAYMENTS created.Table CUSTOMERS altered.Table CUSTOMERS altered.Table BOOKINGS altered. Name Null? Type _____________ ___________ ________________ CUSTOMERID NOT NULL NUMBER FIRSTNAME VARCHAR2(100) LASTNAME VARCHAR2(100) EMAIL NOT NULL VARCHAR2(100) Name Null? Type ______________ ___________ ________________ BOOKINGID NOT NULL NUMBER CUSTOMERID NUMBER BOOKINGDATE DATE DESTINATION VARCHAR2(100) Name Null? Type ______________ ___________ _________ PAYMENTID NOT NULL NUMBER BOOKINGID NUMBER AMOUNT NUMBER PAYMENTDATE DATE TABLE_NAME COLUMN_NAME POSITION STATUS _____________ ______________ ___________ __________ CUSTOMERS EMAIL 1 ENABLED 1 row selected.
Alter the USERS table to change the primary key to Email to ensure uniqueness based on email addresses.
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