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Introduction to Databases and Basic SQL: Key Concepts and Commands, Exams of Computer Science

Queen Mary, University of London (QMUL)Computer Science

Introduction to Databases and Basic SQL: Key Concepts and Commands Introduction to Databases and Basic SQL: Key Concepts and Commands

Typology: Exams

2024/2025

Available from 08/11/2025

Emma_Johnson
Emma_Johnson ๐Ÿ‡ฌ๐Ÿ‡ง

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Introduction to Databases and Basic SQL:
Key Concepts and Commands
1. What does a table in a database represent?
oโœ“ A collection of rows and columns
oA single data entry
oA list of commands
oA programming language
2. In a table, what is a row called?
oโœ“ A record
oA column
oA key
oA field
3. What is a column in a database table?
oโœ“ A set of data values of a particular type
oA single data entry
oA list of rows
oA relation
4. Which SQL command is used to retrieve data?
oโœ“ SELECT
oINSERT
oUPDATE
oDELETE
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Introduction to Databases and Basic SQL:

Key Concepts and Commands

  1. What does a table in a database represent? o โœ“ A collection of rows and columns o A single data entry o A list of commands o A programming language
  2. In a table, what is a row called? o โœ“ A record o A column o A key o A field
  3. What is a column in a database table? o โœ“ A set of data values of a particular type o A single data entry o A list of rows o A relation
  4. Which SQL command is used to retrieve data? o โœ“ SELECT o INSERT o UPDATE o DELETE
  1. Which SQL command adds new data to a table? o SELECT o โœ“ INSERT o UPDATE o DELETE
  2. Which SQL command changes existing data in a table? o SELECT o INSERT o โœ“ UPDATE o DELETE
  3. Which SQL command removes data from a table? o SELECT o INSERT o UPDATE o โœ“ DELETE
  4. What uniquely identifies a record in a database table? o A foreign key o โœ“ A primary key o A column name o An index
  5. What links two tables in a relational database?
  1. What is the difference between a primary key and a foreign key? o Both are the same o Primary key identifies rows, foreign key relates tables โœ“ o Primary key relates tables, foreign key identifies rows o Neither has a specific function
  2. Which command updates the age of employee โ€˜Johnโ€™ to 31? o UPDATE Employees SET Age = 31 WHERE Name = 'John'; โœ“ o INSERT INTO Employees (Age) VALUES (31) WHERE Name = 'John'; o SELECT Age = 31 FROM Employees WHERE Name = 'John'; o DELETE Age FROM Employees WHERE Name = 'John';
  3. How do you delete all records from a table named "Orders"? o DELETE * Orders; o โœ“ DELETE FROM Orders; o REMOVE FROM Orders; o DELETE Records FROM Orders;
  4. What does the term โ€œdata modelโ€ refer to in databases?

o A programming language o A software interface o โœ“ A way to organize data into tables, rows, and columns o A type of database engine

  1. Which of the following best describes a "row"? o A column header o โœ“ A single entry in a table o A database itself o A key column
  2. An attribute in a database corresponds to which element? o Row o โœ“ Column o Table o Record
  3. Which SQL command would you use to add a new column to an existing table? o INSERT COLUMN o UPDATE COLUMN o โœ“ ALTER TABLE o SELECT COLUMN
  4. When writing an SQL SELECT query, which clause filters the records?

o โœ“ Must reference a primary key in another table o Always a number o Must be a text field

  1. Which command is used to change data in an existing row? o โœ“ UPDATE o INSERT o DELETE o MODIFY
  2. How do you retrieve only the "Name" column from a table named "Users"? o SELECT USERS.Name; o SELECT COLUMN Name FROM Users; o โœ“ SELECT Name FROM Users; o GET Name FROM Users;
  3. Consider two tables: Orders (OrderID, CustomerID) and Customers (CustomerID, Name). What is CustomerID in Orders? o Primary key o โœ“ Foreign key o Unique key o Index
  4. What is the purpose of the WHERE clause in SQL?

o To select tables o To join tables o โœ“ To filter records based on a condition o To order results

  1. In SQL, which command would add a new row to a table? o UPDATE o DELETE o SELECT o โœ“ INSERT
  2. What is a composite key? o A single primary key o A foreign key o โœ“ A primary key made up of multiple columns o A key used only for sorting
  3. Which SQL statement would update the salary of employees in department 5? o UPDATE Employees SET Salary=5000; o โœ“ UPDATE Employees SET Salary=5000 WHERE DepartmentID=5; o INSERT Salary=5000 WHERE DepartmentID=5; o DELETE Salary FROM Employees WHERE DepartmentID=5;
  4. How do you remove a column from a table?

o A property of stored procedures o โœ“ Ensures foreign keys correctly reference primary keys o The speed of query execution o The uniqueness of primary keys

  1. Can a table have more than one foreign key? o No o โœ“ Yes o Only if it has no primary key o Only in NoSQL databases
  2. What result does the following SQL produce? SELECT Name FROM Employees WHERE Age > 30; o โœ“ Returns names of employees older than 30 o Returns all names o Returns ages of employees o Throws an error
  3. In a SQL database, what is a โ€œrecordโ€? o A column in a table o โœ“ A row of data in a table o A type of data model o An SQL command
  4. What is the function of the PRIMARY KEY constraint? o Allows duplicate values

o โœ“ Uniquely identifies each row in a table o References other tables o Sorts data

  1. Which statement correctly deletes a record with ID=10 from a table called Products? o DELETE Products WHERE ID=10; o DELETE * FROM Products WHERE ID=10; o โœ“ DELETE FROM Products WHERE ID=10; o REMOVE FROM Products WHERE ID=10;
  2. What does the SQL INSERT INTO statement do? o Deletes data o โœ“ Adds new data to a table o Retrieves data o Updates data
  3. What is the keyword to change existing data? o INSERT o DELETE o โœ“ UPDATE o SELECT
  4. Which of the following describes a foreign key? o A key unique to the table o โœ“ A field that points to a primary key in another table

o ORDER BY o GROUP BY o HAVING

  1. A primary key must have which of the following characteristics? o Allows duplicates o Can be NULL o โœ“ Unique and not NULL o Optional in tables
  2. Why use foreign keys? o To speed up queries o To sort data o โœ“ To maintain relationships between tables o To duplicate data