Useful Queries

1. Print Date and time using sysdate:
    SELECT TO_CHAR (SYSDATE, 'DD-MM-YY HH:MI:SS') FROM DUAL;

2. Print Numbers from 1 to 10.
 SELECT ROWNUM r
      FROM DUAL
CONNECT BY ROWNUM <= 10;

3. Kill Session
alter system kill session '1266,54057'; --'sid, serial#'

4. Gather Schema stats:
begin
DBMS_STATS.GATHER_TABLE_STATS('AP','AP_SUPPLIER_SITES_ALL');
end;
/

5. Remove special  (control chars) characeters from the string

SELECT REGEXP_REPLACE(colx, '[[:cntrl:]]', ' ') FROM xx_tab;

6. REPLACE ONE OR MORE COMMAS WITH SINGLE COMMA AND SPACE

select regexp_replace(' Address Line1,,Addressline3,,Postal Code,,57000  ',',{1,}', ', ') from dual;