一个简单的方法是

UPDATE tbl_name SET fild_name = value WHERE fild_name IS NULL

使用COALESCE，它返回第一个非空值。

SELECT COALESCE(sum(case when c.runstatus = 'Succeeded' then 1 end), 0) as Succeeded

如果返回NULL，则将Succeeded设置为0。

你说的前三列，是指求和列吗?如果是，将ELSE 0添加到CASE语句中。NULL值的SUM为NULL。

sum(case when c.runstatus = 'Succeeded' then 1 else 0 end) as Succeeded, 
sum(case when c.runstatus = 'Failed' then 1 else 0 end) as Failed, 
sum(case when c.runstatus = 'Cancelled' then 1 else 0 end) as Cancelled, 

SQL小提琴演示

在这段代码中包装您的列。

ISNULL(Yourcolumn, 0)

也许检查一下为什么得到null

在case语句中添加else，这样如果没有找到测试条件，它们默认为0。此时，如果没有找到测试条件，则将NULL传递给SUM()函数。

Select c.rundate, 
  sum(case when c.runstatus = 'Succeeded' then 1 else 0 end) as Succeeded, 
  sum(case when c.runstatus = 'Failed' then 1 else 0 end) as Failed, 
  sum(case when c.runstatus = 'Cancelled' then 1 else 0 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

UPDATE TableName SET ColumnName= ISNULL(ColumnName, 0 ) WHERE Id = 10