Ref cursor trouble

Question

Hi All,
My requirement is to fetch values from any given tables through ref cursor, so i have used a below procedure
CREATE OR REPLACE
PROCEDURE et1(
    tab_name IN VARCHAR2,
    c1 OUT sys_refcursor)
AS
  v_prim_val VARCHAR2(2000);
  v_sql      VARCHAR2(2000);
BEGIN
  SELECT wm_concat(s.column_name)
  INTO v_prim_val
  FROM user_cons_columns s ,
    user_constraints c
  WHERE c.constraint_name=s.constraint_name
  AND c.constraint_type  ='P'
  AND s.table_name       =tab_name;
  dbms_output.put_line('Col val='||v_prim_val);
  v_sql:='select '||v_prim_val|| ' from easy where id in (1,2,3)';
  OPEN c1 FOR v_sql;
END et1;
/Problem with above code is the record set returned by ref cursor will be unknown so in which variable should i put it in?
below code will create table for above procedure
create table easy(id integer, event_rowid integer,txn_rowid integer,txn_name varchar2(200));
begin
for i in 1..5 loop
insert into easy values(i,'777'||i,i||89,'Ris'||i||i);
end loop;
end;
commit;
alter table easy add constraint pk_easy primary key(id,event_rowid,txn_name);While googling i found "we can't fetch into a variable of the weak cursor's row type." But I don't know the record set or the variables being returned .
Please help!

Answer 1

983088 wrote:
Is there alternative for wm_concat?Read the FAQ: {message:id=9360005}
under the string aggregation techniques
Thanks Billy for your reply
I had a requirement and i tried something , apparently it's a fiasco
I understand static sql is the key but not for my Lock.
I have 300 tables in my Database ,I have to fetch primary key and there values on some condition which user will pass .So, you're saying a user should be able to extract any data they want from any table of their choice with any conditions they want? Such 'users' are usually technical administrators who know the database and are trusted not to damage things.
Now please tell me when i don't know which table they will pass and table may have any number of primary keys and if i have used dynamic sql so what's wrong in that?It means that your business requirement is too 'generic' and there is no solid design to what the requirements are.
what approach should i follow?Use the DBMS_SQL package. This allows a 'dynamic' query to be constructed, parsed (and thus validated) and then queried where you can fetch the columns by numeric position (column number 1, column number 2 etc.) as well as determining their datatypes and names etc.
An example from my standard library of examples, where I use DBMS_SQL to take any query and extract the details of that query to output the data returned as a CSV file...
As sys user:
CREATE OR REPLACE DIRECTORY TEST_DIR AS '\tmp\myfiles'
GRANT READ, WRITE ON DIRECTORY TEST_DIR TO myuser
/As myuser:
CREATE OR REPLACE PROCEDURE run_query(p_sql IN VARCHAR2
                                     ,p_dir IN VARCHAR2
                                     ,p_header_file IN VARCHAR2
                                     ,p_data_file IN VARCHAR2 := NULL) IS
  v_finaltxt  VARCHAR2(4000);
  v_v_val     VARCHAR2(4000);
  v_n_val     NUMBER;
  v_d_val     DATE;
  v_ret       NUMBER;
  c           NUMBER;
  d           NUMBER;
  col_cnt     INTEGER;
  f           BOOLEAN;
  rec_tab     DBMS_SQL.DESC_TAB;
  col_num     NUMBER;
  v_fh        UTL_FILE.FILE_TYPE;
  v_samefile  BOOLEAN := (NVL(p_data_file,p_header_file) = p_header_file);
BEGIN
  c := DBMS_SQL.OPEN_CURSOR;
  DBMS_SQL.PARSE(c, p_sql, DBMS_SQL.NATIVE);
  d := DBMS_SQL.EXECUTE(c);
  DBMS_SQL.DESCRIBE_COLUMNS(c, col_cnt, rec_tab);
  FOR j in 1..col_cnt
  LOOP
    CASE rec_tab(j).col_type
      WHEN 1 THEN DBMS_SQL.DEFINE_COLUMN(c,j,v_v_val,2000);
      WHEN 2 THEN DBMS_SQL.DEFINE_COLUMN(c,j,v_n_val);
      WHEN 12 THEN DBMS_SQL.DEFINE_COLUMN(c,j,v_d_val);
    ELSE
      DBMS_SQL.DEFINE_COLUMN(c,j,v_v_val,2000);
    END CASE;
  END LOOP;
  -- This part outputs the HEADER
  v_fh := UTL_FILE.FOPEN(upper(p_dir),p_header_file,'w',32767);
  FOR j in 1..col_cnt
  LOOP
    v_finaltxt := ltrim(v_finaltxt||','||lower(rec_tab(j).col_name),',');
  END LOOP;
  --  DBMS_OUTPUT.PUT_LINE(v_finaltxt);
  UTL_FILE.PUT_LINE(v_fh, v_finaltxt);
  IF NOT v_samefile THEN
    UTL_FILE.FCLOSE(v_fh);
  END IF;
  -- This part outputs the DATA
  IF NOT v_samefile THEN
    v_fh := UTL_FILE.FOPEN(upper(p_dir),p_data_file,'w',32767);
  END IF;
  LOOP
    v_ret := DBMS_SQL.FETCH_ROWS(c);
    EXIT WHEN v_ret = 0;
    v_finaltxt := NULL;
    FOR j in 1..col_cnt
    LOOP
      CASE rec_tab(j).col_type
        WHEN 1 THEN DBMS_SQL.COLUMN_VALUE(c,j,v_v_val);
                    v_finaltxt := ltrim(v_finaltxt||',"'||v_v_val||'"',',');
        WHEN 2 THEN DBMS_SQL.COLUMN_VALUE(c,j,v_n_val);
                    v_finaltxt := ltrim(v_finaltxt||','||v_n_val,',');
        WHEN 12 THEN DBMS_SQL.COLUMN_VALUE(c,j,v_d_val);
                    v_finaltxt := ltrim(v_finaltxt||','||to_char(v_d_val,'DD/MM/YYYY HH24:MI:SS'),',');
      ELSE
        DBMS_SQL.COLUMN_VALUE(c,j,v_v_val);
        v_finaltxt := ltrim(v_finaltxt||',"'||v_v_val||'"',',');
      END CASE;
    END LOOP;
  --  DBMS_OUTPUT.PUT_LINE(v_finaltxt);
    UTL_FILE.PUT_LINE(v_fh, v_finaltxt);
  END LOOP;
  UTL_FILE.FCLOSE(v_fh);
  DBMS_SQL.CLOSE_CURSOR(c);
END;This allows for the header row and the data to be written to seperate files if required.
e.g.
SQL> exec run_query('select * from emp','TEST_DIR','output.txt');
PL/SQL procedure successfully completed.Output.txt file contains:
empno,ename,job,mgr,hiredate,sal,comm,deptno
7369,"SMITH","CLERK",7902,17/12/1980 00:00:00,800,,20
7499,"ALLEN","SALESMAN",7698,20/02/1981 00:00:00,1600,300,30
7521,"WARD","SALESMAN",7698,22/02/1981 00:00:00,1250,500,30
7566,"JONES","MANAGER",7839,02/04/1981 00:00:00,2975,,20
7654,"MARTIN","SALESMAN",7698,28/09/1981 00:00:00,1250,1400,30
7698,"BLAKE","MANAGER",7839,01/05/1981 00:00:00,2850,,30
7782,"CLARK","MANAGER",7839,09/06/1981 00:00:00,2450,,10
7788,"SCOTT","ANALYST",7566,19/04/1987 00:00:00,3000,,20
7839,"KING","PRESIDENT",,17/11/1981 00:00:00,5000,,10
7844,"TURNER","SALESMAN",7698,08/09/1981 00:00:00,1500,0,30
7876,"ADAMS","CLERK",7788,23/05/1987 00:00:00,1100,,20
7900,"JAMES","CLERK",7698,03/12/1981 00:00:00,950,,30
7902,"FORD","ANALYST",7566,03/12/1981 00:00:00,3000,,20
7934,"MILLER","CLERK",7782,23/01/1982 00:00:00,1300,,10-----
Billy ,BTW u made my day i was just telling my girlfriend i got a reply from Oracle Ace, THXSmall things please ....