SQL question replacing case statement TSQL SQL server 2000

Appreciate if someone can do a quick QA on this code and let me know if I am on the right track.

the SQL belongs to a stored procedue of a large Web system. I do not have the development enviorenment for the entire system, but need a change to one of the stored prcedures so its kind of very hard to do full testing.

the existing code extracts a hard coded string (DCode)  depending on the Descr in the ClassMaster table.  But new requirements are DCode can change. So we built a new table with a link to ClassMaster ( DGCodes ). The new table cotains the DCode that the user can edit.

I just want to make sure the new SQL code does teh same job as before.

 
here is the table structure

DGCodes table
ClassId			Descr		DCode
000000001G00000001YN	A	                 1
0000000033000000001M	B	                 2
00000000880000000014	C	         	3

ClassMaster  table
ClassId			Descr						 
000000001G00000001YN	A	                 
0000000033000000001M	B
00000000880000000014	C

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here is the Existing code

Select 
		case c.Descr 
			When 'A' then '1'
			When 'B' then '2'	
			When 'C' then '3'			
			else ''
		end as DCode
	from ClassMaster c join PartMain im on c.ClassId = im.ClassId

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here is the new code

Select 	DGCodes.DCode 			 
	from DGCodes join join PartMain im on im.ClassId = DGCodes.ClassId

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