Master SQL for Data Analysis - Sequential Numbers

The video tutorial explains the use of the row_number window function in SQL to assign sequential numbers to rows within partitions, such as listing users by age in each city. It covers the syntax, steps to create results, and filtering techniques using inline views to extract specific rows based on their row number.

What is the primary purpose of the row_number window function?

• To calculate the sum of a column

• To create a sequential integer for each row within a group

• To delete duplicate rows in a table

• To assign a unique identifier to each database

In the row_number function, what does the 'partition by' clause do?

• It sorts the entire result set

• It divides the result set into groups based on a specified column

• It calculates the average of a column

• It filters out rows with null values

How does the 'order by' clause affect the row_number function?

• It determines the order in which rows are numbered within each partition

• It filters rows based on a condition

• It groups rows by a specified column

• It resets the row number for each new partition

What is the result of using a filter where row_number equals one?

• It selects the last row from each partition

• It selects the first row from each partition

• It selects all rows in the result set

• It selects rows with null values

How can you modify the query to get the top five oldest users in each city?

• Change the filter to row_number not equal to five

• Change the filter to row_number equal to five

• Change the filter to row_number less than or equal to five

• Change the filter to row_number greater than five