sql - 如果有空值，如何忽略select语句中的列

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 NULL 值消失，只显示具有正确数据的列。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 sql-server然后只需将结果集复制到临时表中，然后尝试以下查询。

使用动态sql。
将总行数与具有空值的总行数进行比较。
如果两个计数相同，则排除该特定列，否则包括。

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)