标量函数降低效率实现表值函数的功效

1、标量函数：NumericReplaceXX(b.AlarmDesc, [Message])

 

2、执行以下语句报错，在此应该使用表值函数

update Csc050.cscstd20.dbo.d_activealarm set AlarmLevel = b.AlarmCodeLevel, AlarmDesc = .dbo.NumericReplaceXX(b.AlarmDesc, [Message]) 
  ,AlarmClass = b.AlarmClass, AlarmLogicClass = b.AlarmLogicClass, AlarmDeviceEffect = b.AlarmDeviceEffect, AlarmBuinessEffect = b.AlarmBuinessEffect
     from Csc050.cscstd20.dbo.d_activealarm a inner join Csc050.cscstd20.dbo.E_告警分类表 b
   on a.AlarmCode = b.ConId

3、修改为case when 语句 实现功能

update Csc050.cscstd20.dbo.d_activealarm set AlarmLevel = b.AlarmCodeLevel, AlarmDesc = case when a.AlarmDesc is not null or a.AlarmDesc is null then .dbo.NumericReplaceXX(b.AlarmDesc, [Message]) else a.AlarmDesc  end
  ,AlarmClass = b.AlarmClass, AlarmLogicClass = b.AlarmLogicClass, AlarmDeviceEffect = b.AlarmDeviceEffect, AlarmBuinessEffect = b.AlarmBuinessEffect
     from Csc050.cscstd20.dbo.d_activealarm a inner join Csc050.cscstd20.dbo.E_告警分类表 b
   on a.AlarmCode = b.ConId