Understanding MySQL: Queries and Joins

What is the primary purpose of normalisation in a relational database?

• To increase the size of the database

• To reduce data redundancy and improve data integrity

• To make the database more complex

• To decrease the speed of data retrieval

Which of the following is a type of join in SQL?

• INNER JOIN

• OUTER JOIN

• LEFT JOIN

• All of the above

In a relational database, what does a foreign key do?

• Uniquely identifies each record in a table

• Establishes a relationship between two tables

• Increases the speed of queries

• Stores large binary objects

Which SQL clause is used to filter records?

• SELECT

• WHERE

• ORDER BY

• GROUP BY

Which normal form is achieved when a table is free of transitive dependencies?

• First Normal Form (1NF)

• Second Normal Form (2NF)

• Third Normal Form (3NF)

• Boyce-Codd Normal Form (BCNF)

What does the SQL command `JOIN` do?

• Combines rows from two or more tables based on a related column

• Deletes rows from a table

• Updates existing records in a table

• Inserts new records into a table

Which of the following is NOT a benefit of normalisation?

• Improved data integrity

• Reduced data redundancy

• Increased complexity of queries

• Easier maintenance

What is the purpose of the `ON` clause in a SQL JOIN statement?

• To specify the columns to be selected

• To define the condition for joining tables

• To order the results

• To group the results

Which of the following SQL statements is used to retrieve data from a database?

• INSERT

• UPDATE

• DELETE

• SELECT