Which statement creates a composite key?
Which statement creates a composite key?
A composite key is created by combining two or more columns to form a unique key for a table. In option D, the statement 'PRIMARY KEY(OrderID, OrderItemID)' specifies a primary key that consists of both OrderID and OrderItemID columns. This combination ensures that each row is uniquely identified by the combined values of these two columns, forming a composite key.
At 3:00 P.M. (1500 hours), you create a backup of your database. At 4:00 P.M. (1600 hours), you create a table named Customer and import data into the table.
At 5:00 P.M. (1700 hours), your server fails.
You run a script to apply only the 3:00 P.M. backup to your database. What is the result of the script?
When you restore a database using a backup created at 3:00 P.M., the database will return to the state it was in at that time. Since the Customer table was created at 4:00 P.M., which is after the backup was taken, it would not exist in the restored database. Therefore, the Customer table no longer exists after applying the backup.
In which situation do you need to perform a restore on a database?
A restore on a database is performed when data becomes corrupted in the database. This process recovers the database to a previous state before the corruption occurred, ensuring that data integrity is maintained. Other options listed do not necessarily require a full restore; for example, rolling back a transaction can be done without restoring the entire database, and encountering an application error or needing to delete data do not inherently involve restoring the database.
Which command should you use to give a user permission to read the data in a table?
The correct command to give a user permission to read the data in a table is 'GRANT SELECT'. This is a common SQL command used to assign the SELECT privilege to a user, allowing them to read (select) data from the specified table.
You need to enable a new employee to authenticate to your database.
Which command should you use?
To enable a new employee to authenticate to your database, you need to create a new user account for them. The correct SQL command for this purpose is 'CREATE USER'. This command defines a new user in the database system, allowing the new employee to log in and access the database as per the permissions granted.