Questions

What is the purpose of Common Table Expressions (CTEs) in SQL?

 

• To perform aggregate calculations on grouped records
• To define and store a temporary result set for the duration of a query
• To encapsulate complex queries and improve query readability and maintainability

 

You have two tables, “Product Inventory” and “Products Sold”. The tables have the same columns and you want to combine their records. However, you want to keep the records from both tables separate and display them as distinct sets. Which SQL operation should you use in this scenario?

 

• ORDER BY
• GROUP BY
• UNION
• JOIN

 

Which statement is used to extract specified fields from a table?

 

• SELECT
• GET
• OPEN
• EXTRACT

 

Which function which returns the average value of the column?

 

• AVG()
• MEAN()
• SUM()
• MEDIAN()

 

How do you select a column named “campaign” from a table named “media”?

 

• EXTRACT campaign FROM media
• SELECT campaign FROM media
• SELECT media.campaign

 

You are writing a query and would like to know the total impressions that have been delivered per campaign, per supply_source, and per device_type. Which of the following represents how you should write the query?

 

• SELECT campaign, supply_source, device_type, SUM(impressions) AS impressions FROM dsp_impressions GROUP BY 1,2,3
• SELECT campaign, supply_source, SUM(impressions) AS impressions FROM device_type GROUP BY 1,2
• SELECT total_impressions SUM(impressions) AS device_type FROM campaign, supply_source GROUP BY 1,2,3