如何计算SQL列中的出现次数？

Question

I have a table that lists the following values. Some of the values in column 1 show up twice for the same customer (for example apple could show up 2 or more times.)

Column 1
Apples
Oranges
Bananas

I know I can use this to get the count for each of the values.

SELECT column 1, COUNT(*)
FROM table
GROUP BY column 1

Is there a way to write a SQL statement that looks at when the count of one of those values shows up twice for the same customer?

For example, I want to find out how many times apple shows up twice for the same customer.

Answer 1

Assuming you have a customer column, your query could look like this:

SELECT customer, column1, COUNT(*)
FROM table
GROUP BY customer, column1
HAVING COUNT(*) > 1;

This will show you a customer field, and your column1 (the column with Apple and Banana and so on), and the number of times the combination of these fields occur. The GROUP BY will ensure that the count is calculated correctly. The HAVING will only show records where the COUNT value is > 1 after the grouping has occurred.