sp_lock (Transact-SQL MetaData) Definition

Please note: that the following source code is provided and copyrighted by Microsoft and is for educational purpose only.
The meta data is from an SQL 2012 Server.

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Definition:

sys.sp_lock(int @spid1
, int @spid2)

MetaData:

 create procedure sys.sp_lock -- - 1996/04/08 00:00  
@spid1 int = NULL,        --  server process id to check for locks  --   
@spid2 int = NULL        --  other process id to check for locks  --   
as  
  
set nocount on  
--   
--   Show the locks for both parameters.  
 --   
set transaction isolation level read committed  
if @spid1 is not NULL  
begin  
    select     convert (smallint, req_spid) As spid,  
        rsc_dbid As dbid,  
        rsc_objid As ObjId,  
        rsc_indid As IndId,  
        substring (v.name, 1, 4) As Type,  
        substring (rsc_text, 1, 32) as Resource,  
        substring (u.name, 1, 8) As Mode,  
        substring (x.name, 1, 5) As Status  
  
    from     master.dbo.syslockinfo,  
        master.dbo.spt_values v,  
        master.dbo.spt_values x,  
        master.dbo.spt_values u  
  
    where   master.dbo.syslockinfo.rsc_type = v.number  
            and v.type = 'LR'  
            and master.dbo.syslockinfo.req_status = x.number  
            and x.type = 'LS'  
            and master.dbo.syslockinfo.req_mode + 1 = u.number  
            and u.type = 'L'  
  
            and req_spid in (@spid1, @spid2)  
end  
  
--   
--   No parameters, so show all the locks.  
 --   
else  
begin  
    select     convert (smallint, req_spid) As spid,  
        rsc_dbid As dbid,  
        rsc_objid As ObjId,  
        rsc_indid As IndId,  
        substring (v.name, 1, 4) As Type,  
        substring (rsc_text, 1, 32) as Resource,  
        substring (u.name, 1, 8) As Mode,  
        substring (x.name, 1, 5) As Status  
  
    from     master.dbo.syslockinfo,  
        master.dbo.spt_values v,  
        master.dbo.spt_values x,  
        master.dbo.spt_values u  
  
    where   master.dbo.syslockinfo.rsc_type = v.number  
            and v.type = 'LR'  
            and master.dbo.syslockinfo.req_status = x.number  
            and x.type = 'LS'  
            and master.dbo.syslockinfo.req_mode + 1 = u.number  
            and u.type = 'L'  
    order by spid  
end  
  
return (0) --  sp_lock