Question

如果表T1具有带有数据库的单列c1（a，a，b，b，b，c）编写一个输出为

的查询

a  2
b  3

Answer 1

试试这个：

SELECT c1, COUNT(*)
FROM T1
GROUP BY c1
HAVING COUNT(*) > 1

Answer 2

SELECT
    'a',
    2
UNION ALL
SELECT
    'b',
    3

Answer 3

SELECT c1, count(*) FROM T1 GROUP BY c1 HAVING count(*) > 1