Delimited list output

Question

I'd like to get a comma-delimited list of user email addresses from a table. I want to do it in a single select since I'm going to embed it into anther select. In SQL Server the following works:
create table users (user_id varchar(10), email varchar(100))
declare @email varchar(2000)
SELECT @email = @email + email + '; ' FROM users
How can I do this in Oracle (8i)?

Answer 1

It sounds like you need Tom Kyte's str2tbl function as well as his stragg function. In the following example, I just left out the additional tables and join conditions, but it should work the same with them.
scott@ORA92> -- test table and test data:
scott@ORA92> create table hts_assay -- ha
  2    (assay_name varchar2(5),
  3       assay_id   varchar2(10),
  4       assay_type     varchar2(100))
  5  /
Table created.
scott@ORA92> insert all
  2  into hts_assay values ('name1', 'id1', 'type1a')
  3  into hts_assay values ('name1', 'id1', 'type1b')
  4  into hts_assay values ('name1', 'id1', 'type1c')
  5  into hts_assay values ('name2', 'id2', 'type2a')
  6  into hts_assay values ('name2', 'id2', 'type2b')
  7  into hts_assay values ('name3', 'id3', 'type3')
  8  into hts_assay values ('name4', 'id4', 'type4')
  9  select * from dual
10  /
7 rows created.
scott@ORA92> commit
  2  /
Commit complete.
scott@ORA92> --
scott@ORA92> -- code from Tom Kyte for stragg function:
scott@ORA92> create or replace type string_agg_type as object
  2  (
  3       total varchar2(4000),
  4 
  5       static function
  6            ODCIAggregateInitialize(sctx IN OUT string_agg_type )
  7            return number,
  8 
  9       member function
10            ODCIAggregateIterate(self IN OUT string_agg_type ,
11                        value IN varchar2 )
12            return number,
13 
14       member function
15            ODCIAggregateTerminate(self IN string_agg_type,
16                          returnValue OUT  varchar2,
17                          flags IN number)
18            return number,
19 
20       member function
21            ODCIAggregateMerge(self IN OUT string_agg_type,
22                      ctx2 IN string_agg_type)
23            return number
24  );
25  /
Type created.
scott@ORA92> create or replace type body string_agg_type
  2  is
  3 
  4  static function ODCIAggregateInitialize(sctx IN OUT string_agg_type)
  5  return number
  6  is
  7  begin
  8        sctx := string_agg_type( null );
  9        return ODCIConst.Success;
10  end;
11 
12  member function ODCIAggregateIterate(self IN OUT string_agg_type,
13                             value IN varchar2 )
14  return number
15  is
16  begin
17        self.total := self.total
18        || ','
19        || value;
20        return ODCIConst.Success;
21  end;
22 
23  member function ODCIAggregateTerminate(self IN string_agg_type,
24                               returnValue OUT varchar2,
25                               flags IN number)
26  return number
27  is
28  begin
29        returnValue := ltrim(self.total,',');
30        return ODCIConst.Success;
31  end;
32 
33  member function ODCIAggregateMerge(self IN OUT string_agg_type,
34                           ctx2 IN string_agg_type)
35  return number
36  is
37  begin
38        self.total := self.total || ctx2.total;
39        return ODCIConst.Success;
40  end;
41 
42 
43  end;
44  /
Type body created.
scott@ORA92> CREATE or replace
  2  FUNCTION stragg(input varchar2 )
  3  RETURN varchar2
  4  PARALLEL_ENABLE AGGREGATE USING string_agg_type;
  5  /
Function created.
scott@ORA92> -- code from Tom Kyte for str2tbl function:
scott@ORA92> create or replace type myTableType as table of varchar2(100);
  2  /
Type created.
scott@ORA92> create or replace function str2tbl( p_str in varchar2 )
  2  return myTableType
  3  as
  4        l_str      long default p_str || ',';
  5        l_n         number;
  6        l_data    myTableType := myTabletype();
  7  begin
  8        loop
  9            l_n := instr( l_str, ',' );
10            exit when (nvl(l_n,0) = 0);
11            l_data.extend;
12            l_data( l_data.count ) := ltrim(rtrim(substr(l_str,1,l_n-1)));
13            l_str := substr( l_str, l_n+1 );
14        end loop;
15        return l_data;
16  end;
17  /
Function created.
scott@ORA92> --
scott@ORA92> -- usage of stragg and str2tbl functions within a procedure
scott@ORA92> -- that has a ref cursor as an out parameter
scott@ORA92> CREATE OR REPLACE PROCEDURE your_procedure
  2    (xcur_spcur  OUT sys_refcursor,
  3       p_assaylist IN     VARCHAR2)
  4  AS
  5  BEGIN
  6    OPEN xcur_spcur FOR
  7    SELECT ha.assay_name, STRAGG (ha.assay_type) AS AssayResultTypes
  8    FROM   hts_assay ha
  9    WHERE  ha.assay_id IN
10             (SELECT *
11              FROM   TABLE (CAST (str2tbl (p_assaylist) AS mytableType)))
12    GROUP  BY ha.assay_name;
13  END your_procedure;
14  /
Procedure created.
scott@ORA92> SHOW ERRORS
No errors.
scott@ORA92> VARIABLE g_ref REFCURSOR
scott@ORA92> VARIABLE g_assaylist VARCHAR2(60)
scott@ORA92> EXEC :g_assaylist := 'id1,id2,id3'
PL/SQL procedure successfully completed.
scott@ORA92> EXECUTE your_procedure (:g_ref, :g_assaylist)
PL/SQL procedure successfully completed.
scott@ORA92> PRINT g_ref
ASSAY ASSAYRESULTTYPES
name1 type1a,type1b,type1c
name2 type2a,type2b
name3 type3