Function to step through a View

Question

Hello All, I need to create a function that reads a view and exports the data into a fixed field formatted file. I believe I need to step through the view, and for each record, extract each field, rpad it to a specified length and concatenate the fields back together into a new record, perhaps dumping each new record into a temp table and once done, export the table into a file. Please let me know if this reasoning sounds logical and/or is the best approach. Thanks.

Answer 1

If you want something a little more generic to take any query (whether from a view or regular tables), something along these lines will do...
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
        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,,10The procedure allows for the header and data to go to seperate files if required. Just specifying the "header" filename will put the header and data in the one file.
Adapt to output different datatypes and styles are required.