Use CASE inside SUM or COUNT to compute multiple metrics in one pass.
Use CASE inside SUM or COUNT to compute multiple metrics in one pass. Read the query line by line and identify the input table, the transformation, and the shape of the result before running it.
SELECT SUM(CASE WHEN amount >= 2000 THEN 1 ELSE 0 END) AS large_orders, COUNT(*) AS all_orders FROM orders;
Before running the example, predict the output columns and whether the query returns one row, many rows, or possibly no rows.
In your own words, explain the main SQL feature in today’s lesson and why it answers the question.
Recall prompt: Sum a CASE expression that returns 1 for large orders, else 0. Close this page section mentally and explain the query from memory before proceeding.
Count large orders (amount at least 2000) and all orders in one query.
Sum a CASE expression that returns 1 for large orders, else 0.