Declare @maxVersion int,@strYear varchar(2),@strMonth varchar(2),@strYearMonth varchar(4)
 Set @strYear  = Right(Cast(Datepart(yy,Getdate()) AS varchar(4)),2)
 Set @strMonth =  Cast(Datepart(mm,Getdate()) AS varchar(4))
 if (Len(@strMonth) = 1)
  Set @strMonth = '0' + @strMonth
  
 Set @strYearMonth = @strYear + @strMonth
 
 select @maxVersion = max(BomVersion) from TBL_Bom Where MaterialNo = @MaterialNo
  
 --当最大值无效,或当前月份有大于最大值月份时
 if (@maxVersion is null OR @maxVersion = 0 OR  Cast(@strYearMonth AS Int)  >  @maxVersion / 100) 
  set @BomNewVersion = Cast( (@strYearMonth + '01') AS int)
 else
  Set @BomNewVersion = @maxVersion + 1

三个SUBSTRING
Sql server 中 SELECT x = SUBSTRING('abcdef', 1,len('abcdef'))
c#  中：  string x = SUBSTRING('abcdef', 0,len('abcdef'))
javascript中：string x = SUBSTR('abcdef', 0,len('abcdef'))
稍微有点区别。