sql - SQL 请求中缺少行，其中计数为 0(按值范围分组)

Question

我的 SQL 请求中存在一些缺失行的问题。我想显示按值分组的出现次数，并且即使它们在间隔中没有值，表格也需要显示它们。

这是现在显示的内容

|---------------------|------------------|
|      Category       |       Amount     |
|---------------------|------------------|
|        <= 0         |        34        |
|---------------------|------------------|
|       ]0 - 1]       |        18        |
|---------------------|------------------|
|         > 2         |        25        |
|---------------------|------------------|

这就是我需要它显示的内容

|---------------------|------------------|
|      Category       |       Amount     |
|---------------------|------------------|
|        <= 0         |        34        |
|---------------------|------------------|
|       ]0 - 1]       |        18        |
|---------------------|------------------|
|       ]1 - 2]       |        0         |
|---------------------|------------------|
|         > 2         |        25        |
|---------------------|------------------|

到目前为止我的代码是:

SELECT  t.range AS Category,
      Count( * )  AS [Amount],
      FROM (
           SELECT value,
                  CASE 
                     WHEN (value <= 0) THEN ' <= 0 ' 
                     WHEN (value > 0 AND value <= 1) THEN ' ]0 - 1]' 
                     WHEN (value > 1 AND value <= 2) THEN ' ]1 - 2]' 
                     WHEN (value > 2 ) THEN ' > 2 ' 
                  END AS range
            FROM Table
       )
       t
GROUP BY t.range;

关于如何解决这个问题有什么想法吗？

谢谢你了!

Answer 1

只需执行多个查询，然后将它们全部合并:

SELECT ' <= 0 ' AS category, count(*) as Amount FROM MyTable WHERE value <= 0
UNION ALL
SELECT ' ]0 - 1]' AS category, count(*) FROM MyTable WHERE value > 0 AND value <= 1
UNION ALL
SELECT ' ]1 - 2]' AS category, count(*) FROM MyTable WHERE value > 1 AND value <= 2
UNION ALL
SELECT ' > 2 ' AS category, count(*) FROM MyTable WHERE value > 1 AND value > 2