Describe Relational Concepts DP-900 Practice Questions (Page 4)

Questions 16–20

1. 16foundation · easy

   In a relational database, what is a table?

   • AA file that stores unstructured text data
   • BA graphical representation of data relationships
   • CA set of key-value pairs
   • DA collection of related data organized into rows and columns
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2. 17application · medium

   A database has a large Orders table with millions of rows. A frequent query filters on the CustomerID column to find all orders for a specific customer. The query currently performs a full table scan and is slow. You need to improve the performance of this query without changing the query itself. What should you do?

   • ANormalize the Orders table into multiple tables.
   • BAdd a foreign key constraint on CustomerID.
   • CCreate a view that selects all columns from Orders.
   • DCreate an index on the CustomerID column.
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4. 18expert · hard

   A database has a large Orders table with columns OrderID (primary key), CustomerID, OrderDate, and TotalAmount. Queries frequently filter on CustomerID and OrderDate, and also sort by OrderDate. The database administrator is considering adding an index. Which indexing strategy is most effective for these queries?

   • ACreate a composite index on (CustomerID, OrderDate).
   • BCreate a clustered index on OrderDate.
   • CCreate an index on TotalAmount.
   • DCreate a separate index on CustomerID and another on OrderDate.
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5. 19application · medium

   A new employee, Jane Doe, needs to be added to the Employees table. The table has columns: EmployeeID (identity column, auto-generated), FirstName, LastName, DepartmentID. The DepartmentID for Jane is 5. Which SQL statement correctly adds Jane?

   • AINSERT INTO Employees VALUES ('Jane', 'Doe', 5);
   • BUPDATE Employees SET FirstName = 'Jane', LastName = 'Doe', DepartmentID = 5;
   • CINSERT INTO Employees (EmployeeID, FirstName, LastName, DepartmentID) VALUES (NULL, 'Jane', 'Doe', 5);
   • DINSERT INTO Employees (FirstName, LastName, DepartmentID) VALUES ('Jane', 'Doe', 5);
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6. 20foundation · easy

   What is the role of a table in a relational database?

   • ATo manage network connections to the database
   • BTo store database backup files
   • CTo store data in a structured format that can be queried
   • DTo define user permissions for database access
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