SQL> set colsep ","
SQL> select object_id,object_name from all_objects where rownum<2;

OBJECT_ID,OBJECT_NAME
----------,------------------------------
20,ICOL$

SQL> set colsep "|"
SQL> select object_id,object_name from all_objects where rownum<2;

OBJECT_ID|OBJECT_NAME
----------|------------------------------
20|ICOL$

SQL> set colsep " "
SQL> select object_id,object_name from all_objects where rownum<2;

OBJECT_ID OBJECT_NAME
---------- ------------------------------
20 ICOL$

SQL> set colsep test
SQL> select object_id,object_name from all_objects where rownum<2;

OBJECT_IDtestOBJECT_NAME
----------test------------------------------
20testICOL$