选择列中每个不同值的计数

Question

我试图选择包含两列的结果集：

• 列的DISTINCT值。
• 该值在表格列中显示的次数。

这句话（有点）说明了我试图做的事情：

SELECT DISTINCT ID AS X,
(SELECT COUNT(*) FROM #t WHERE ID = X)
FROM #t
ORDER BY X;

所需的结果集如下所示：

| ID   | COUNT
|------|------
| 0    | 12
| 1    | 16
| 2    | 4

Answer 1

SELECT   ID AS X,
         COUNT(*) AS "COUNT"
FROM     #t
GROUP BY ID
ORDER BY X

Answer 2

这只是使用GROUP BY：

的简单聚合

SELECT ID, COUNT(*)
FROM #t
GROUP BY ID
ORDER BY ID;

Answer 3

SELECT   ID AS X,
         COUNT(1) AS "COUNT"
FROM     #t
GROUP BY ID
ORDER BY ID

使用Group By

您的查询（相关子查询）也应该有效。根据GordonLinoff的说法，在查询中将ID替换为ID，它应该可以正常工作。

SELECT DISTINCT ID AS X,
(SELECT COUNT(*) FROM #t WHERE ID = X)
FROM #t
ORDER BY ID ;