在 SQL 服务器查询中用 0 替换 NULL [英] Replacing NULL with 0 in a SQL server query

问题描述

我开发了一个查询，在前三列的结果中我得到 NULL.如何用 0 替换它?

I have developed a query, and in the results for the first three columns I get NULL. How can I replace it with 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

推荐答案

当您想用其他内容替换可能的 null 列时，请使用 IsNull.

When you want to replace a possibly null column with something else, use IsNull.

SELECT ISNULL(myColumn, 0 ) FROM myTable

如果 myColumn 首先为空，这将在其中放置一个 0.

This will put a 0 in myColumn if it is null in the first place.

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