Code:
SQL>
SQL> show version
Oracle SQLDeveloper Command-Line (SQLcl) version: 4.2.0.17.073.1038
SQL>
SQL> -- csv format: technique 1
SQL>
SQL> select /*csv*/ * from scott.emp;
"EMPNO","ENAME","JOB","MGR","HIREDATE","SAL","COMM","DEPTNO"
7369,"SMITH","CLERK",7902,17-DEC-80,800,,20
7499,"ALLEN","SALESMAN",7698,20-FEB-81,1600,300,30
7521,"WARD","SALESMAN",7698,22-FEB-81,1250,500,30
7566,"JONES","MANAGER",7839,02-APR-81,2975,,20
7654,"MARTIN","SALESMAN",7698,28-SEP-81,1250,1400,30
7698,"BLAKE","MANAGER",7839,01-MAY-81,2850,,30
7782,"CLARK","MANAGER",7839,09-JUN-81,2450,,10
7788,"SCOTT","ANALYST",7566,19-APR-87,3000,,20
7839,"KING","PRESIDENT",,17-NOV-81,5000,,10
7844,"TURNER","SALESMAN",7698,08-SEP-81,1500,0,30
7876,"ADAMS","CLERK",7788,23-MAY-87,1100,,20
7900,"JAMES","CLERK",7698,03-DEC-81,950,,30
7902,"FORD","ANALYST",7566,03-DEC-81,3000,,20
7934,"MILLER","CLERK",7782,23-JAN-82,1300,,10
14 rows selected.
SQL>
SQL> -- csv format: technique 2
SQL>
SQL> set sqlformat delimited ,
SQL>
SQL> -- now all queries will return data in csv format
SQL>
SQL> select * from scott.emp;
"EMPNO","ENAME","JOB","MGR","HIREDATE","SAL","COMM","DEPTNO"
7369,"SMITH","CLERK",7902,17-DEC-80,800,,20
7499,"ALLEN","SALESMAN",7698,20-FEB-81,1600,300,30
7521,"WARD","SALESMAN",7698,22-FEB-81,1250,500,30
7566,"JONES","MANAGER",7839,02-APR-81,2975,,20
7654,"MARTIN","SALESMAN",7698,28-SEP-81,1250,1400,30
7698,"BLAKE","MANAGER",7839,01-MAY-81,2850,,30
7782,"CLARK","MANAGER",7839,09-JUN-81,2450,,10
7788,"SCOTT","ANALYST",7566,19-APR-87,3000,,20
7839,"KING","PRESIDENT",,17-NOV-81,5000,,10
7844,"TURNER","SALESMAN",7698,08-SEP-81,1500,0,30
7876,"ADAMS","CLERK",7788,23-MAY-87,1100,,20
7900,"JAMES","CLERK",7698,03-DEC-81,950,,30
7902,"FORD","ANALYST",7566,03-DEC-81,3000,,20
7934,"MILLER","CLERK",7782,23-JAN-82,1300,,10
14 rows selected.
SQL>