Computer Science for IGCSE & O level - Databases (Section 4)

• 1

  In the context of database design, what is the primary purpose of a primary key?

  คำตอบ

  (B)

  To uniquely identify each record in a table.
• 2

  What is the purpose of a primary key in a database table?

  คำตอบ

  (B)

  To uniquely identify each row (record) in the table.
• 3

  What does the SQL command `COUNT(*)` do?

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  (B)

  Counts the total number of rows in a table.
• 4

  Which of the following are valid types of relationships that can exist between tables in a database?

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  A

  B

  D
• 5

  Which SQL statement is used to add a new column to a table?

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  (B)

  ALTER TABLE ... ADD COLUMN
• 6

  Which of the following is NOT typically a component of a database system?

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  (D)

  The operating system kernel.
• 7

  Which command is used to remove data from a table?

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  (B)

  DELETE FROM
• 8

  What is the role of fields in the context of databases?

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  (C)

  To define individual pieces of data within a record.
• 9

  What is a 'join' in SQL used for?

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  (A)

  To combine data from two or more tables
• 10

  Which keyword is used in SQL to retrieve all columns from a table?

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  (A)

  *
• 11

  Which of the following is an advantage of using a database system?

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  B

  C

  D
• 12

  Which are the benefits of using SQL?

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  A

  B

  C

  D
• 13

  Which of the following statements is true about indexes in database?

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  (B)

  Indexes speed up data retrieval.
• 14

  What is the main advantage of using databases?

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  (B)

  Databases prevent problems because if any changes or additions are made it only has to be done once.
• 15

  What are the characteristics of a primary key?

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  (C)

  It uniquely identifies each record in a table.
• 16

  Which is used to ensure data consistency?

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  A

  B

  C

  D
• 17

  Which of the following is a characteristic of a well-designed database?

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  (C)

  Efficient data retrieval.
• 18

  Which data type would be used to store true/false values?

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  (C)

  BOOLEAN
• 19

  What is the difference between `TRUNCATE` and `DELETE` statements?

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  (A)

  TRUNCATE is faster and removes all rows, while DELETE is slower and removes specific rows.
• 20

  What does the acronym SQL stand for?

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  (B)

  Structured Query Language
• 21

  What is the purpose of the HAVING clause in SQL?

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  (A)

  To filter rows based on conditions applied to aggregate functions.
• 22

  Which component of an SQL command specifies the table to retrieve data from?

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  (C)

  FROM
• 23

  In the context of a database, what does 'record' refer to?

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  (C)

  A row in a table.
• 24

  What is the main purpose of using a database management system (DBMS)?

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  (B)

  To manage and organize data efficiently.
• 25

  Which SQL statement is used to update data in a table?

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  (C)

  UPDATE
• 26

  What is data normalization primarily used for in database design?

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  (B)

  To reduce data redundancy and improve data integrity.
• 27

  What is a view in a database?

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  (B)

  A virtual table based on the result-set of an SQL statement.
• 28

  What is the primary purpose of data validation in a database?

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  (A)

  To ensure data accuracy and consistency.
• 29

  What are the two main components in a database?

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  (C)

  Data and Schema
• 30

  Which data type would be best suited for storing a unique ID (e.g., customer ID) that is an integer?

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  (B)

  INTEGER
• 31

  What does the `COUNT(*)` function typically return in SQL?

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  (B)

  The number of rows that meet a certain criteria.
• 32

  Which of the following data types is used to store large blocks of text?

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  (C)

  TEXT
• 33

  In the context of a database, what is a 'record'?

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  (B)

  A single instance of an entity in a table.
• 34

  What is the purpose of an index in a database?

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  (B)

  To speed up data retrieval.
• 35

  What does the term 'referential integrity' refer to in the context of databases?

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  (B)

  The consistency of data across related tables.
• 36

  What are the fundamental principles of database normalization aimed at?

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  (B)

  Reducing data redundancy and improving data integrity.
• 37

  What does the `WHERE` clause in an SQL query typically do?

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  (C)

  Filters the results based on a condition.
• 38

  What is the purpose of a database trigger?

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  (B)

  To automatically execute a set of actions in response to a specific event on a table.
• 39

  Which of the following can be a validation rule?

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  A

  B

  C
• 40

  Which data type would be most appropriate for storing the ward number of a patient in a hospital database?

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  (B)

  Integer
• 41

  Which SQL command is used to remove data from a database table?

  คำตอบ

  (C)

  DELETE
• 42

  In SQL, what does the `INSERT` statement do?

  คำตอบ

  (B)

  Adds new data into a table.
• 43

  In SQL, what does the FROM clause specify?

  คำตอบ

  (B)

  The table to retrieve data from.
• 44

  Which of the following is a task typically performed by a database administrator (DBA)?

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  A

  B

  C
• 45

  What does the `SELECT` statement in SQL typically do?

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  (B)

  Retrieves data from one or more tables.
• 46

  What is the purpose of an index in a database?

  คำตอบ

  (B)

  To speed up data retrieval.
• 47

  Which SQL command is used to remove a table from a database?

  คำตอบ

  (B)

  DROP TABLE
• 48

  What does the `WHERE` clause do in an SQL query?

  คำตอบ

  (C)

  Filters the data based on specified conditions.
• 49

  What is a key characteristic of a primary key field?

  คำตอบ

  (C)

  It uniquely identifies each record.
• 50

  What is the purpose of normalization in database design?

  คำตอบ

  (B)

  To eliminate data redundancy and improve data integrity.