Master SQL for Data Analysis - Query Data (SELECT)

The video tutorial introduces the SQL SELECT statement, explaining its role in retrieving data from databases. It covers the basic structure of SQL queries, including selecting specific columns, using wildcards, and performing calculations. The tutorial also discusses different types of tables, such as virtual, derived, and temporary tables, and their applications. Additionally, it highlights SQL syntax, keywords, and best practices, including the use of comments and limiting data retrieval. The video aims to build foundational knowledge of SQL queries, preparing viewers for more advanced topics.

What is the primary purpose of the SELECT statement in SQL?

• To delete data from a database

• To insert data into a database

• To update data in a database

• To retrieve data from a database

Which clause is used to specify the data source in a SQL query?

• FROM

• ORDER BY

• WHERE

• GROUP BY

How can you retrieve all columns from a table in SQL?

• SELECT all FROM table_name

• SELECT everything FROM table_name

• SELECT * FROM table_name

• SELECT columns FROM table_name

What is the purpose of using the GROUP BY clause in SQL?

• To join tables

• To filter rows

• To sort rows

• To group rows for aggregation

Which function can be used to round a number in a SQL query?

• ROUND()

• CEIL()

• FLOOR()

• TRUNCATE()

What is a virtual table in SQL?

• A table that is used to view data without storing it

• A table that is used for temporary data storage

• A table that stores data permanently

• A table that is created by joining multiple tables

What is a derived table in SQL?

• A table created by querying another SQL query

• A table that stores data permanently

• A table that is used for temporary data storage

• A table that is used to view data without storing it

How can you add a single-line comment in SQL?

• Using // comment

• Using /* comment */

• Using -- comment

• Using # comment

What is the purpose of the LIMIT clause in SQL?

• To limit the number of tables

• To limit the size of the database

• To limit the number of rows returned

• To limit the number of columns

Why is it important to use comments in SQL queries?

• To document the purpose and logic of the query

• To reduce the size of the database

• To prevent the query from running

• To increase the execution speed