如何在 col3 的特定条件下获取 col1 和 col2 的每个组合的计数

Posted 2023-03-24

【中文标题】如何在 col3 的特定条件下获取 col1 和 col2 的每个组合的计数

【英文标题】：How to get count for each combination of col1 & col2 on specific conditions for col3

【发布时间】：2017-05-02 21:15:17

【问题描述】：

表：我在 SQL Server 2012 中有一个数据库表 table_name2，其数据为：

col1    col2    col3
one     first   abc-3ab9-cd-f-01
two     second  abcdefg04
three   first   
three   second  mnopqrs03
one     first   NULL
two     first   'NULL' 
one     second  papapap
two     second  dbrf434
two     first   434jhpo

DDL：并使用

创建它

CREATE TABLE [dbo].[table_name2](
    [col1] [nvarchar](255) NULL,
    [col2] [nvarchar](255) NULL,
    [col3] [nvarchar](255) NULL
) ON [PRIMARY];

数据填充：

insert into table_name2
values ('one','first','abc-3ab9-cd-f-01'),
('two','second','abcdefg04'),
('three','first',''),
('three','second','mnopqrs03'),
('one','first',NULL),
('two','first','NULL'),
('one','second','papapap'),
('two','second','dbrf434'),
('two','first','434jhpo');

我想列出 col1 和 col2 的每个组合。然后计算每个 col1/col2 组合的 col3，其中 col3 为空白、'N/A'、NULL 或'NULL'。

对于那些与 col3 相关的条件都不满足的 col1/col2 组合，我想为这些组合显示 0。

我想要的结果是：

col1    col2    MainCount
one     first   1
one     second  0
three   first   1
three   second  0
two     first   1
two     second  0

我尝试过的：现在我尝试了一个简单的查询和它的两个修改版本

SELECT col1, col2, count(col3) as MainCount
FROM table_name2
WHERE col3 is null OR col3 = '' OR col3 = 'N/A' OR col3 = 'Unknown' OR col3 = 'NULL'
GROUP BY col1, col2
ORDER BY col1, col2;

给予：

col1    col2    MainCount
one     first   0
three   first   1
two     first   1

那么

SELECT col1, col2, count(col3) as MainCount
FROM table_name2
WHERE col3 =
    CASE WHEN
        (col3 is null OR col3 = '' OR col3 = 'N/A' OR col3 = 'Unknown' OR col3 = 'NULL')
         THEN col3 ELSE NULL
    END
GROUP BY col1, col2
ORDER BY col1, col2;

给予：

col1    col2    MainCount
three   first   1
two     first   1

最后一个

SELECT col1, col2, count(CASE WHEN col3 is not null THEN col3 ELSE 0 END) as MainCount  
FROM table_name2
WHERE col3 is null OR col3 = '' OR col3 = 'N/A' OR col3 = 'Unknown' OR col3 = 'NULL'
GROUP BY col1, col2
ORDER BY col1, col2;

给出错误：

Conversion failed when converting the nvarchar value 'NULL' to data type int.

我在这里做错了什么，如何获得所需的输出？

【参考方案1】：

在count 中包含这些条件。

SELECT col1, col2,
count(case when col3 is null OR col3 = '' OR col3 = 'N/A' OR col3 = 'Unknown' OR col3 = 'NULL' then 1 end) as MainCount
FROM table_name2
GROUP BY col1, col2
ORDER BY col1, col2;

【讨论】：

感谢大家的意见。所有建议的解决方案都有效，但我接受 vkp 答案，因为它最接近我的方法并且首先发布。

【参考方案2】：

select col1, col2
  , sum(case 
      when col3 is null then 1 
      when col3 in('','N/A','Unknown','NULL') then 1
      else 0
      end) as MainCount
from table_name2
group by col1, col2
order by col1, col2

rextester 演示：http://rextester.com/QBOJ61516

返回：

+-------+--------+-----------+
| col1  |  col2  | MainCount |
+-------+--------+-----------+
| one   | first  |         1 |
| one   | second |         0 |
| three | first  |         1 |
| three | second |         0 |
| two   | first  |         1 |
| two   | second |         0 |
+-------+--------+-----------+

【参考方案3】：

这是因为 col3 不包含数字，但您在 case 语句中使用了 0。试试这个：

SELECT col1
,col2
,sum(CASE WHEN col3 is null THEN 1
          WHEN col3 in ('', 'N/A', 'Unknown', 'NULL') THEN 1
          ELSE 0 END) as MainCount  
FROM table_name2
GROUP BY col1, col2
ORDER BY col1, col2;

【参考方案4】：

试试这个，如果有任何疑问，请告诉我。

select col1,col2,sum(case when col3 IS NULL OR COL3 in ('NULL', '', 'N/A') THEN 1 ELSE 0 END) AS MAINCOUNT from table_name2
group by col1,col2
ORDER BY COL1,COL2;