[Program 1] - Lesson 4 - Calculate Bussiness Metrics In SQL

How do you use the CASE WHEN statement to categorize data?

• Use CASE WHEN to perform mathematical calculations on data.

• CASE WHEN is used to join multiple tables in SQL.

• Use CASE WHEN to categorize data by defining conditions and corresponding outputs for each category.

• You can only use CASE WHEN in SELECT statements, not in WHERE clauses.

Name three common aggregate functions used in SQL.

• SUM, AVG, COUNT

• FIRST

• MIN

• MAX

How does the HAVING clause differ from the WHERE clause?

• The HAVING clause is used for sorting results, while the WHERE clause is for filtering.

• The HAVING clause filters aggregated results, while the WHERE clause filters individual records.

• The HAVING clause can only be used with SELECT statements, whereas the WHERE clause can be used with any SQL command.

• The HAVING clause applies to all records, while the WHERE clause only applies to aggregated data.

What is the correct syntax for the GROUP BY statement?

• SELECT * FROM table_name GROUP BY;

• SELECT column1, column2, ... FROM table_name GROUP BY column1, column2, ...;

• SELECT column1, column2 FROM table_name GROUP BY column1;

• SELECT column1, column2 FROM table_name GROUP BY;

Can you group by multiple columns in SQL? If so, how?

• Yes, you can group by multiple columns in SQL by listing them in the GROUP BY clause.

• You must use a JOIN clause to group by multiple columns.

• Grouping by multiple columns is not allowed in SQL.

• You can only group by one column in SQL.

What is the role of the GROUP BY clause in SQL?

• The GROUP BY clause is used to delete rows from a table.

• The GROUP BY clause sorts the results in ascending order.

• The GROUP BY clause groups rows that have the same values in specified columns into summary rows.

• The GROUP BY clause filters rows based on a condition.

How can you use aggregate functions with the GROUP BY clause?

• You can use aggregate functions like COUNT, SUM, AVG with the GROUP BY clause to summarize data based on specified columns.

• You can only use aggregate functions with the ORDER BY clause.

• GROUP BY is used to filter rows, not to summarize data.

• Aggregate functions cannot be used with GROUP BY in SQL.

How do you filter results after grouping them in SQL?

• Use the HAVING clause to filter results after grouping.

• Use the SELECT statement to filter results without grouping.

• Apply the ORDER BY clause to sort results after grouping.

• Use the WHERE clause to filter results before grouping.

Can you use the CASE WHEN statement within an aggregate function?

• No, CASE WHEN cannot be used in aggregate functions.

• You can only use CASE WHEN in SELECT statements, not in aggregates.

• CASE WHEN is only for filtering data, not for aggregation.

• Yes, you can use CASE WHEN within an aggregate function.

What is the difference between COUNT(*) and COUNT(column_name) in SQL?

• COUNT(*) counts only non-NULL values; COUNT(column_name) counts all rows.

• COUNT(*) and COUNT(column_name) are identical in function.

• COUNT(*) counts all rows; COUNT(column_name) counts non-NULL values in the specified column.

• COUNT(*) counts unique values; COUNT(column_name) counts all values.