x y
A P
A P
B P
B Q
Hi, I need a query to return for all unique values of x, how many different y's. So for the above data it would return:
x count
A 1
B 2
Thanks
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2 Answers
Use GROUP BY and COUNT(DISTINCT ...):
SELECT x, COUNT(DISTINCT y) AS cnt_y
FROM yourtable
GROUP BY x
Result:
x cnt_y A 1 B 2
Test data:
CREATE TABLE yourtable (x VARCHAR(100) NOT NULL, y VARCHAR(100) NOT NULL);
INSERT INTO yourtable (x, y) VALUES
('A', 'P'),
('A', 'P'),
('B', 'P'),
('B', 'Q');
Comments
This is the simple case for a GROUP BY statement.
Here's some code:
SELECT x, COUNT(DISTINCT y) AS y
FROM table
GROUP BY x;
