What does the following SQL statement do: SELECT Customer, COUNT(Order) FROM Sales GROUP BY Customer HAVING COUNT(Order) >5
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Selects all Customers from the Sales table
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Selects all customers from table Sales that have made more than 5 orders.
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Selects the total number of orders from the Sales table, if this number is greater than 5
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Selects no records
The HAVING clause filters groups after the GROUP BY aggregation. This query first groups sales records by customer, counts orders per customer, then returns only those customers whose order count exceeds 5. Option A misses the HAVING filter. Option C incorrectly describes the aggregation scope. Option D is false because the query will return records for customers meeting the condition.
To answer this question, we need to understand the different components of the SQL statement:
SELECT Customer, COUNT(Order): This part of the statement selects the 'Customer' column and counts the number of occurrences of 'Order' for each customer.
FROM Sales: This specifies that we are selecting data from the 'Sales' table.
GROUP BY Customer: This groups the data by the 'Customer' column, so that we get the count of orders for each customer separately.
HAVING COUNT(Order) > 5: This filters the results and only selects the records where the count of orders for a customer is greater than 5.
Let's go through each option to understand why it is correct or incorrect:
Option A) Selects all Customers from the Sales table - This option is incorrect because the statement is not selecting all customers. It is selecting customers who have made more than 5 orders.
Option B) Selects all customers from table Sales that have made more than 5 orders - This option is correct because the statement is grouping the data by customer and selecting only those customers who have made more than 5 orders.
Option C) Selects the total number of orders from the Sales table if this number is greater than 5 - This option is incorrect because the statement is not selecting the total number of orders. It is selecting customers who have made more than 5 orders.
Option D) Selects no records - This option is incorrect because the statement will select records if there are customers who have made more than 5 orders.
The correct answer is B) Selects all customers from the table Sales that have made more than 5 orders. This option is correct because the SQL statement filters the results to only include customers who have made more than 5 orders.