如果select语句中的列具有空值，则如何忽略该列

Question

我有以下查询：

SELECT WC_WARD_CATEGORY,
   MAX(CASE WHEN months = 'JAN' THEN BOR END) JAN,
   MAX(CASE WHEN months = 'FEB' THEN BOR END) FEB,
   MAX(CASE WHEN months = 'MAR' THEN BOR END) MAR,
   MAX(CASE WHEN months = 'APR' THEN BOR END) APR,
   MAX(CASE WHEN months = 'MAY' THEN BOR END) MAY,
   MAX(CASE WHEN months = 'JUN' THEN BOR END) JUN,
   MAX(CASE WHEN months = 'JUL' THEN BOR END) JUL,
   MAX(CASE WHEN months = 'AUG' THEN BOR END) AUG,
   MAX(CASE WHEN months = 'SEP' THEN BOR END) SEP,
   MAX(CASE WHEN months = 'OCT' THEN BOR END) OCT,
   MAX(CASE WHEN months = 'NOV' THEN BOR END) NOV,
   MAX(CASE WHEN months = 'DEC' THEN BOR END) DEC
FROM bor2
GROUP BY WC_WARD_CATEGORY

它给了我以下输出：

我想要的只是要消失的NULL值，只显示具有适当数据的列。所以我希望OCT，NOV和DEC出现在输出中而不是其他列中。是否可以使用SQL？

Answer 1

如果sql-server然后只是将结果集复制到临时表中，然后尝试以下查询。

使用动态sql 将总行数与总行数为null进行比较 如果两个计数都相同，则排除其他包含的特定列。

<强>查询

SELECT WC_WARD_CATEGORY,
   MAX(CASE WHEN months = 'JAN' THEN BOR END) JAN,
   MAX(CASE WHEN months = 'FEB' THEN BOR END) FEB,
   MAX(CASE WHEN months = 'MAR' THEN BOR END) MAR,
   MAX(CASE WHEN months = 'APR' THEN BOR END) APR,
   MAX(CASE WHEN months = 'MAY' THEN BOR END) MAY,
   MAX(CASE WHEN months = 'JUN' THEN BOR END) JUN,
   MAX(CASE WHEN months = 'JUL' THEN BOR END) JUL,
   MAX(CASE WHEN months = 'AUG' THEN BOR END) AUG,
   MAX(CASE WHEN months = 'SEP' THEN BOR END) SEP,
   MAX(CASE WHEN months = 'OCT' THEN BOR END) OCT,
   MAX(CASE WHEN months = 'NOV' THEN BOR END) NOV,
   MAX(CASE WHEN months = 'DEC' THEN BOR END) DEC 
INTO #temp
FROM bor2 
GROUP BY   WC_WARD_CATEGORY;

然后，

declare @strsql varchar(max)
  set @strsql = 'select '
  set @strsql += 
  (select case when  (select COUNT(*) from #temp where JAN is null ) 
  <> (select count(*) from #temp ) then 'JAN, ' else '' end)
  set @strsql += 
  (select case when  (select COUNT(*) from #temp  where FEB is null) 
  <> (select count(*) from #temp ) then 'FEB, ' else '' end)
  set @strsql += 
  (select case when  (select COUNT(*) from #temp  where MAR is null) 
  <> (select count(*) from #temp ) then 'MAR, ' else '' end)
  set @strsql += 
  (select case when  (select COUNT(*) from #temp  where APR is null) 
  <> (select count(*) from #temp ) then 'APR, ' else '' end)
  set @strsql += 
  (select case when  (select COUNT(*) from #temp  where MAY is null) 
  <> (select count(*) from #temp ) then 'MAY, ' else '' end)
  set @strsql += 
  (select case when  (select COUNT(*) from #temp  where JUN is null) 
  <> (select count(*) from #temp ) then 'JUN, ' else '' end)
  set @strsql += 
  (select case when  (select COUNT(*) from #temp  where JUL is null) 
  <> (select count(*) from #temp ) then 'JUL, ' else '' end)
  set @strsql += 
  (select case when  (select COUNT(*) from #temp  where AUG is null) 
  <> (select count(*) from #temp ) then 'AUG, ' else '' end)
  set @strsql += 
  (select case when  (select COUNT(*) from #temp  where SEP is null) 
  <> (select count(*) from #temp ) then 'SEP, ' else '' end)
  set @strsql += 
  (select case when  (select COUNT(*) from #temp  where OCT is null) 
  <> (select count(*) from #temp ) then 'OCT, ' else '' end)
  set @strsql += 
  (select case when  (select COUNT(*) from #temp  where NOV is null) 
  <> (select count(*) from #temp ) then 'NOV, ' else '' end)
  set @strsql += 
  (select case when  (select COUNT(*) from #temp  where DEC is null) 
  <> (select count(*) from #temp ) then 'DEC, ' else '' end)
  set @strsql = LEFT(@strsql,len(@strsql) -1)
  set @strsql += ' from #temp'

  exec (@strsql)

Answer 2

还使用动态SQL，但使用数据透视表：

declare @pc varchar(max)

select @pc = isnull(@pc + ',', '') + mnths
  from (
select distinct '[' + months + ']' mnths, convert(date, '1 ' + months + ' 1') ord
  from (select months
          from bor2
         group by months, WC_WARD_CATEGORY 
        having max(bor) is not null) as a ) as b order by ord

declare @sql varchar(max)
select @sql = '
select *
 from 
(
select WC_WARD_CATEGORY, months, bor
  from bor2
) as SourceTable 
PIVOT
(
max(bor) 
for months in (' + @pc + ')
) as PivotTable;'

execute(@sql)

Answer 3

请检查这是否解决了您的问题

SELECT * FROM WC_WARD_CATEGORY FOR XML PATH('NotNull')

这将为您提供一个XML文件，其中每行只有空列，然后根据您的需要，您可以应用XSLT或脚本任务以此表格格式获取此输入的结果。