How to stop csv from converting string to number in PL/SQL - oracle

Question

I have used a PL/SQL code to export data to csv file.The code is similar to below code:
CREATE OR REPLACE PROCEDURE export_to_csv IS
v_file UTL_FILE.file_type;
v_string VARCHAR2(4000);
CURSOR c_emp IS
SELECT empno, ename, deptno, sal, comm
FROM emp;
BEGIN
v_file := UTL_FILE.fopen('CSVDIR', 'empdata.csv', 'w', 1000);
-- if you do not want heading then remove below two lines v_string := 'Emp Code, Emp Name, Dept, Salary, Commission'; UTL_FILE.put_line (v_file, v_string);
FOR cur IN c_emp LOOP
v_string := cur.empno || ',' || cur.ename || ',' || cur.deptno || ',' ||cur.sal || ',' || cur.comm;
UTL_FILE.put_line(v_file, v_string);
END LOOP;
UTL_FILE.fclose(v_file);
EXCEPTION
WHEN OTHERS THEN
IF UTL_FILE.is_open(v_file) THEN
UTL_FILE.fclose(v_file);
END IF;
END;
/
But one column which datatype is varchar2 is getting converted to number and hence loss of data is occuring.Could anyone please tell me how to stop the conversion?

Answer 1

There is probably no conversion and/or data loss at all. You can test it if you read the file you created. The result should be the same as you see it when you open it in Notepad++. If it's true that Notepad++ shows all the data then there's nothing lossed. So, create the file and read it afterwards. Compare the data with the result and you will know.
create or replace PROCEDURE read_csv IS
v_file UTL_FILE.file_type;
v_string VARCHAR2(4000);
BEGIN
v_file := UTL_FILE.fopen('CSVDIR', 'empdata.csv', 'r', 1000);
LOOP
UTL_FILE.GET_LINE(v_file, v_string);
DBMS_OUTPUT.PUT_LINE(v_string);
END LOOP;
UTL_FILE.fclose(v_file);
EXCEPTION
WHEN OTHERS THEN
IF UTL_FILE.is_open(v_file) THEN
UTL_FILE.fclose(v_file);
END IF;
END;
--
-- R e s u l t
--
-- anonymous block completed
-- 7369,SMITH,20,800,
-- 7499,ALLEN,30,1600,300
-- 7521,WARD,30,1250,500
-- 7566,JONES,20,2975,
-- 7654,MARTIN,30,1250,1400
-- 7698,BLAKE,30,2850,
-- 7782,CLARK,10,2450,
-- 7788,SCOTT,20,3000,
-- 7839,KING,10,5000,
-- 7844,TURNER,30,1500,0
-- 7876,ADAMS,20,1100,
-- 7900,JAMES,30,950,
-- 7902,FORD,20,3000,
-- 7934,MILLER,10,1300,