Computer Science for IGCSE & O level - Databases (Section 6)
1
Which clause is used to sort the records in an SQL query?
2
What is the purpose of a validation rule for a field?
Trả lời(B)
To ensure data accuracy and consistency
3
Which SQL command is used to remove a table from a database?
4
Which of the following is an example of a data type?
5
What is the benefit of using a database system over a simple file system for storing data?
Trả lời(B)
Databases offer better data organization, data integrity, and allow for more efficient data retrieval.
6
What does the term 'data warehousing' refer to?
Trả lời(C)
A system for storing and analyzing large volumes of historical data.
7
What is the purpose of the `GROUP BY` clause in SQL?
Trả lời(C)
To combine rows with the same values in a specified column into a summary row.
8
Which SQL command is used to change existing data in a table?
9
What is the purpose of the `GROUP BY` clause in an SQL query?
Trả lời(C)
To combine rows that have the same values in one or more columns into a summary row.
10
What are the benefits of using a database?
11
In a database, what does the term 'field' represent?
Trả lời(B)
A single item of data within a record.
12
What is the purpose of a SQL script?
Trả lời(B)
To perform a task on a database.
13
What is the main function of a database management system (DBMS)?
Trả lời(C)
To manage and organize data.
14
What is the main function of a 'query' in a database?
Trả lời(B)
To retrieve or manipulate data.
15
What is the purpose of the 'WHERE' clause in an SQL query?
Trả lời(C)
To filter the results based on specified criteria.
16
What is a transaction in the context of databases?
Trả lời(B)
A logical unit of work that is treated as a single operation.
17
What is a database index used for?
Trả lời(A)
To speed up data retrieval.
18
What is the purpose of the `ROLLBACK` statement in a database transaction?
Trả lời(B)
To discard the changes made during a transaction and restore the database to its previous state.
19
What is a primary key used for in a database table?
Trả lời(B)
To ensure the unique identification of each record in the table.
20
What is a transaction in a database context?
Trả lời(B)
A sequence of operations performed as a single unit of work.
21
What is the primary function of the `GROUP BY` clause in SQL?
Trả lời(C)
To aggregate data based on one or more columns.
22
What is a field in a database table?
Trả lời(B)
The individual piece of information stored in a database.
23
Which of the following is an example of a database relationship?
24
What is the purpose of the `FROM` clause in an SQL statement?
Trả lời(B)
To identify the table(s) from which to retrieve data.
25
What is data redundancy in a database?
Trả lời(B)
The duplication of data within the database.
26
Which of the following are part of the ACID properties?
27
Which keyword is used to add a primary key to a table?
Trả lời(B)
ALTER TABLE ... ADD PRIMARY KEY
28
In the context of a database table, what is a 'field' also known as?
29
Which of the following data types would be most appropriate for storing a person's date of birth?
30
Which of the following is a type of database relationship?
31
Which components must be set up in database?
32
What is the role of a 'data type' in a database?
Trả lời(B)
To determine how data is stored and displayed.
33
What is the purpose of using a database management system (DBMS)?
34
Which of the following is a key component of database design?
35
In an SQL query, what does the `NULL` value represent?
Trả lời(C)
A missing or unknown value.
36
Which of the following is an example of a DDL command?
37
What does ACID properties stand for in database transaction?
Trả lời(A)
Atomicity, Consistency, Isolation, Durability
38
In SQL, what does the `UPDATE` statement allow you to do?
39
What does a database table store?
Trả lời(B)
Data organized in rows and columns.
40
Which command is used to insert new data into a database table?
41
What type of data should be stored in a column with the data type `VARCHAR`?
Trả lời(C)
Text strings of varying lengths.
42
What is a foreign key used for?
43
What are the purposes of using indexes in a database?
Trả lời(A)
To speed up data retrieval
44
Which of the following is a key advantage of using a relational database?
Trả lời(C)
Ease of data retrieval and manipulation.
45
Which factors should be considered when choosing a data type for a database field?
46
What does the acronym DDL stand for in the context of databases?
47
What is the purpose of `JOIN` command in SQL?
Trả lời(C)
To combine rows from two or more tables based on a related column.
48
What is the main goal of the validation rules?
49
Which of the following is often used to identify multiple records in a relational database?
50
What is the purpose of a 'constraint' in a database?
Trả lời(B)
To enforce rules and restrictions on data.
