sp_MSmatchkey (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_MSmatchkey(nvarchar @tablename
, nvarchar @col1
, nvarchar @col2
, nvarchar @col3
, nvarchar @col4
, nvarchar @col5
, nvarchar @col6
, nvarchar @col7
, nvarchar @col8
, nvarchar @col9
, nvarchar @col10
, nvarchar @col11
, nvarchar @col12
, nvarchar @col13
, nvarchar @col14
, nvarchar @col15
, nvarchar @col16)

MetaData:

   
create proc sys.sp_MSmatchkey  
    @tablename nvarchar(517),  
    @col1 nvarchar(258),  
    @col2 nvarchar(258) = null,  
    @col3 nvarchar(258) = null,  
    @col4 nvarchar(258) = null,  
    @col5 nvarchar(258) = null,  
    @col6 nvarchar(258) = null,  
    @col7 nvarchar(258) = null,  
    @col8 nvarchar(258) = null,  
    @col9 nvarchar(258) = null,  
    @col10 nvarchar(258) = null,  
    @col11 nvarchar(258) = null,  
    @col12 nvarchar(258) = null,  
    @col13 nvarchar(258) = null,  
    @col14 nvarchar(258) = null,  
    @col15 nvarchar(258) = null,  
    @col16 nvarchar(258) = null  
as  
  
    create table #t1 (        --  Join into this...  --   
        i                    int                NOT NULL,  
        name                nvarchar(258)     COLLATE database_default   NULL  
    )  
  
    create table #i1 (  
        i                    int                NOT NULL  
    )  
  
    declare @id int, @ii int, @colnotfound nvarchar(258), @keycnt int  
    select @id = object_id(@tablename)  
    if (@id is null) begin  
        RAISERROR (15001, -1, -1, @tablename)  
        return 1  
    end  
    select @ii = 1  
    insert #t1 values (1, @col1)  
    insert #t1 values (2, @col2)  
    insert #t1 values (3, @col3)  
    insert #t1 values (4, @col4)  
    insert #t1 values (5, @col5)  
    insert #t1 values (6, @col6)  
    insert #t1 values (7, @col7)  
    insert #t1 values (8, @col8)  
    insert #t1 values (9, @col9)  
    insert #t1 values (10, @col10)  
    insert #t1 values (11, @col11)  
    insert #t1 values (12, @col12)  
    insert #t1 values (13, @col13)  
    insert #t1 values (14, @col14)  
    insert #t1 values (15, @col15)  
    insert #t1 values (16, @col16)  
    delete #t1 where name is null  
  
    select @colnotfound = min(name) from #t1 where name not in (select name from dbo.syscolumns where id = @id)  
    if (@colnotfound is not null) begin  
        RAISERROR (14305, -1, -1, @colnotfound, @tablename)  
        return 1  
    end  
    select @ii = 1, @keycnt = count(*) from #t1  
  
    --  Load all indexes which have the matching number of columns into a temp table, then eliminate those which don't qualify.  --   
    --  Remember the RID in the nc index is counted as a key  --   
    insert #i1 select indid from dbo.sysindexes where status & 0x1800 <> 0  
        and id = @id and keycnt - (case indid when 1 then 0 else 1 end) = @keycnt  
    while (@ii <= @keycnt) begin  
        delete #i1 from #i1 i, #t1 t where t.i = @ii and index_col(@tablename, i.i, t.i) <> t.name  
        select @ii = @ii + 1  
    end  
  
    --  The qualifying key will be the lowest indid (or the ONLY indid, if we disallow duplicate indexes), if any remain.  --   
    select name from dbo.sysindexes where id = @id and indid = (select min(i) from #i1)