sql - 在 SQL Server 查询中将 NULL 替换为 0

Question

我开发了一个查询，在前三列的结果中我得到NULL。如何将其替换为 0？

Select c.rundate, 
  sum(case when c.runstatus = 'Succeeded' then 1 end) as Succeeded, 
  sum(case when c.runstatus = 'Failed' then 1 end) as Failed, 
  sum(case when c.runstatus = 'Cancelled' then 1 end) as Cancelled, 
  count(*) as Totalrun from
  (    Select a.name,case when b.run_status=0 Then 'Failed' when b.run_status=1 Then 'Succeeded'
  when b.run_status=2 Then 'Retry' Else 'Cancelled' End as Runstatus,
  ---cast(run_date as datetime)
              cast(substring(convert(varchar(8),run_date),1,4)+'/'+substring(convert(varchar(8),run_date),5,2)+'/'          +substring(convert(varchar(8),run_date),7,2) as Datetime) as RunDate
  from msdb.dbo.sysjobs as a(nolock) inner join msdb.dbo.sysjobhistory as b(nolock) 
  on a.job_id=b.job_id
  where a.name='AI'
  and b.step_id=0) as c
  group by 
  c.rundate

Answer 1

当您想用其他内容替换可能为空的列时，请使用 IsNull .

SELECT ISNULL(myColumn, 0 ) FROM myTable

如果 myColumn 一开始就为空，这将在 myColumn 中放入 0。