declare @TableName nvarchar(100),@Sql nvarchar(1000)

set @TableName = 'YY_TEST.dbo.gh_ghzdk  b'

    set @sql=N'select @CountApp=count(*) '+
         N'from AppointList a' +
         N'left join ' + @TableName +'  on a.MedicalNo=b.blh and dbo.f_IsSameDate(a.AppointTime,b.ghrq)=1' +
         N'where AppointTime >= @S_BeginTime and AppointTime<= @S_EndTime and b.blh is null and a.cancel=0'
    exec sp_executesql @sql,N'@S_BeginTime datetime,@S_EndTime datetime,@CountApp int output',@S_BeginTime,@S_EndTime,@CountApp output

下边注释掉的是可以正常运行的
    /*
    select @CountAppNo=count(*) --爽约人数,算出爽约率就行了，在对赴约进行重复记录Distinc是，可能去掉预约多科室的情况。
    from AppointList a 
    left join YY_TEST.dbo.gh_ghzdk b on a.MedicalNo=b.blh and dbo.f_IsSameDate(a.AppointTime,b.ghrq)=1
    where AppointTime >= @S_BeginTime and AppointTime<= @S_EndTime and b.blh is null and a.cancel=0
    */