(=                                                                           
Description: Pivoting a result of any select statement

Parameters:
  sel_stmt: any valid select statement
  row_cols: optional row columns (used in the outer group by clause)
  col_col : column name for pivoting
  agg_col : column name with values for aggregation
  agg_fn  : aggregation function name (min, max, avg, sum, ...)
  tmp_tbl : global temporary table name
  null_ind: null indicator
  rc      : output: SQLCODE returned
  msg     : output: message text returned
  stmt    : output: statement executed by routine
                                                                  
Example:                                                        

call pivot(
'select * from table(values
  (''grp1'', 1, ''one'', 1)
, (''grp1'', 1, ''two'', 10)
, (''grp1'', 1, ''one'', 2)
, (''grp1'', 2, ''two'', 20)
, (''grp2'', 1, ''one'', 100)
, (''grp2'', 1, ''one'', 200)
) t (grp1, grp2, col_col, agg_col)'
, 'grp1, grp2'
, 'col_col'
, 'agg_col'
, 'sum'
, 'session.tab1'
, '-'
, ?, ?, ?
)

Result set 1
--------------

GRP1 GRP2        one         two        
---- ----------- ----------- -----------
grp1           1           3          10
grp1           2           -          20
grp2           1         300           -
=)

create procedure pivot(
  in  sel_stmt varchar(4000)
, in  row_cols varchar(200)
, in  col_col  varchar(128)
, in  agg_col  varchar(128)
, in  agg_fn   varchar(10)
, in  tmp_tbl  varchar(128)
, in  null_ind varchar(10)
, out rc       int
, out msg      varchar(128)
, out stmt     varchar(4000)
)
LANGUAGE SQL
DYNAMIC RESULT sets 1
BEGIN
 declare QUOT1        char(1) default '''';
 declare QUOT2        char(1) default '"';
 declare SQLCODE      int default 0;
 declare SQLTYPE_ID   int;
 declare SQLTYPE      varchar(128);
 declare SQLLENGTH    int;
 declare SQLSCALE     int;
 declare SQLNAME_DATA varchar(128);
 declare SQLTYPEF     varchar(128);
 declare col_val      varchar(4000);
 declare apo          varchar(1);
 declare l1 RESULT_set_LOCATOR VARYING;

 declare c2 cursor for s2;
 declare c_out cursor with return for s_out;

 declare EXIT HANDLER FOR SQLEXCEPTION
 BEGIN
   GET DIAGNOSTICS EXCEPTION 1 MSG = MESSAGE_TEXT;
   set RC = SQLCODE;
 END;

 set col_col=upper(col_col);
 set agg_col=upper(agg_col);
 -- insert result of select statement into temp table
 set stmt = 'describe '||sel_stmt;
 call SYSPROC.ADMIN_CMD(stmt);
 set stmt = '';
 associate result set locator (l1)
 with procedure SYSPROC.ADMIN_CMD;
 allocate c1 cursor for result set l1;
 open c1;
 fetch c1 into SQLTYPE_ID, SQLTYPE, SQLLENGTH, SQLSCALE, SQLNAME_DATA;
 while (SQLCODE!=100) do
   set SQLTYPEF = SQLTYPE
   ||case 
      when SQLTYPE IN ('DECIMAL', 'DECFLOAT', 'CHARACTER', 'VARCHAR') then 
         '('||RTRIM(CHAR(SQLLENGTH))
       ||case when SQLTYPE='DECIMAL' then ','||RTRIM(CHAR(SQLSCALE)) else '' end
       ||')'                                
      else ''
     end;
   if (col_col=SQLNAME_DATA) then
     set apo = 
      case 
       when SQLTYPE in ('DECIMAL', 'DECFLOAT', 'INTEGER', 'SMALLINT', 'BIGINT', 'REAL', 'DOUBLE') then '' 
       else QUOT1 
      end;
   end if;
   set stmt = stmt||', '||SQLNAME_DATA||' '||SQLTYPEF;
   fetch c1 into SQLTYPE_ID, SQLTYPE, SQLLENGTH, SQLSCALE, SQLNAME_DATA;
 end while;
 close c1;
 set stmt = 
   'declare global temporary table '||tmp_tbl||'('||substr(stmt, 3)
 ||') with replace on commit preserve rows not logged';
 execute immediate stmt;
 set stmt = 'insert into '||tmp_tbl||' '||sel_stmt;
 execute immediate stmt;

 -- construct select statement
 set stmt = 'select distinct rtrim(char('||col_col||')) from '||tmp_tbl||' order by 1';
 prepare s2 from stmt;
 set stmt='';
 open c2;
 fetch c2 into col_val;
 while (SQLCODE!=100) do
   set stmt = 
     stmt||', '||agg_fn||'('
   ||'case when '||col_col||' '
   ||case when col_val is null then 'IS NULL' else ('='||apo||replace(col_val, QUOT1, QUOT1||QUOT1)||apo) end
   ||' then '||agg_col||' end) as '||QUOT2||coalesce(replace(col_val, QUOT2, QUOT2||QUOT2), null_ind)||QUOT2;
   fetch c2 into col_val;
 end while;
 close c2;
 -- add to the select statement groups
 set row_cols = nullif(row_cols, '');
 set stmt = 
   'select '||case when row_cols is not null then row_cols||',' else coalesce(row_cols, '') end
 ||substr(stmt, 2)||' from '||tmp_tbl||' '
 ||case when row_cols is not null then ('group by '||row_cols||' order by '||row_cols) else '' end;
 -- execute this statement
 prepare s_out from stmt;
 open c_out;
END@