Question

有没有办法计算除PrimaryKey列以外的特定记录的空值的所有字段？

Example:

ID  Name    Age    City     Zip

1   Alex    32     Miami    NULL
2   NULL    24     NULL     NULL

作为输出，我需要得到1和3.没有明确指定列名。

Answer 1

declare @T table
(
  ID int,
  Name varchar(10),
  Age int,
  City varchar(10),
  Zip varchar(10)
)  

insert into @T values 
(1, 'Alex', 32, 'Miami', NULL),
(2,  NULL,  24,  NULL,   NULL)

;with xmlnamespaces('http://www.w3.org/2001/XMLSchema-instance' as ns)
select ID,
       (
          select *
          from @T as T2
          where T1.ID = T2.ID
          for xml path('row'), elements xsinil, type 
       ).value('count(/row/*[@ns:nil = "true"])', 'int') as NullCount
from @T as T1

结果：

ID          NullCount
----------- -----------
1           1
2           3

<强>更新

这是一个更好的版本。感谢Martin Smith。

;with xmlnamespaces('http://www.w3.org/2001/XMLSchema-instance' as ns)
select ID,
       (
          select T1.*
          for xml path('row'), elements xsinil, type 
       ).value('count(/row/*[@ns:nil = "true"])', 'int') as NullCount
from @T as T1

<强>更新

使用更快的XQuery表达式。

;with xmlnamespaces('http://www.w3.org/2001/XMLSchema-instance' as ns)
select ID,
       (
          select T1.*
          for xml path('row'), elements xsinil, type 
       ).value('count(//*/@ns:nil)', 'int') as NullCount
from @T as T1

Answer 2

SELECT id,
  CASE WHEN Name IS NULL THEN 1 ELSE 0 END +
  CASE WHEN City IS NULL THEN 1 ELSE 0 END +
  CASE WHEN Zip  IS NULL THEN 1 ELSE 0 END
FROM YourTable

如果您不想在查询中使用显式列名，欢迎使用动态查询

DECLARE @sql NVARCHAR(MAX) = ''
SELECT @sql = @sql + N'  CASE WHEN '+QUOTENAME(c.name)+N' IS NULL THEN 1 ELSE 0 END +'
FROM sys.tables t
JOIN sys.columns c
    ON t.object_id = c.object_id
WHERE 
    c.is_nullable = 1
AND t.object_id = OBJECT_ID('YourTableName')

SET @sql = N'SELECT id, '+@sql +N'+0 AS Cnt FROM [YourTableName]'
EXEC(@sql)

Answer 3

这可以解决您的问题：

select count (id) 
where ( isnull(Name,"") = "" or isnull(City,"") = "" or isnull(Zip,"") = "" )

不是一个聪明的解决方案，但它应该做的工作。

如何在SQL中计算一个记录中包含空值的所有字段？

3 个答案: