如何用PostGreSQL列出两列的非唯一组合?

Question

如何列出两列的非唯一组合?

并得到如下结果:

col A | col B   | count
foo   | bar     | 3
abc   | hello   | 2
def   | world   | 4

如果此组合只存在一次，则不列出:

bob   | alice     | 1

Answer 1

SELECT col_A, col_B, count(*) AS count
FROM your_table
GROUP BY col_A, col_B
HAVING count(*) > 1