Ora-00911 can someone help me

Question

SELECT
(to_char(RLT.DATEFR,'DD-Mon-YYYY') || CHR(13) || ' To ' || CHR(13) || to_char(RLT.DATETO,'DD-Mon-YYYY') ) AS DATECOVERED,
RLT.CHKNO,
RLT.CHKDT,
RLT.RECEIVEDDT,
RLT.AMOUNT,
GEOL.PRO_NAME,
(SELECT nvl(LGUNAME,'') FROM CSRIS_LGUPROF_M WHERE
MUN=BGY.MUN AND PROV=BGY.PROV AND BRGY=BGY.BRGY AND REG=BGY.REG AND ROWNUM='1') AS BRGYDESC,
(SELECT nvl(LGUNAME,'') FROM CSRIS_LGUPROF_M WHERE
MUN=BGY.MUN AND PROV=BGY.PROV AND BRGY IS NULL AND REG=BGY.REG AND ROWNUM='1') AS MUNDESC,
(SELECT nvl(LGUNAME,'') FROM CSRIS_LGUPROF_M WHERE
MUN IS NULL AND PROV=BGY.PROV AND BRGY IS NULL AND REG=BGY.REG AND ROWNUM='1') AS PROVDESC,
(SELECT nvl(LGUNAME,'') FROM CSRIS_LGUPROF_M WHERE
MUN IS NULL AND PROV IS NULL AND BRGY IS NULL AND REG=BGY.REG AND ROWNUM='1') AS REGDESC
FROM CSRIS_RLT_M RLT
JOIN CSRIS_BGYPRF_M BGY ON RLT.BGYPRFID=BGY.BGYPRFID
JOIN CSRIS_PRJ_M PRJ ON BGY.BGYPRFID=PRJ.BGYPRFID
JOIN CSRIS_PROGMON_M PROG ON PRJ.PROGMONID=PROG.PROGMONID
JOIN GEOL_PROJECT_M GEOL ON PROG.PRO_CODE=GEOL.PRO_CODE
where RLT.RECEIVEDDT BETWEEN '01-JAN-2010' and '08-SEP-2010'
and geol.pro_code='BGPF';

Answer 1

ORA-00911:
     invalid character
Cause:      identifiers may not start with any ASCII character other than letters and numbers. $#_ are also allowed after the first character. Identifiers enclosed by doublequotes may contain any character other than a doublequote. Alternative quotes (q'#...#') cannot use spaces, tabs, or carriage returns as delimiters. For all other contexts, consult the SQL Language Reference Manual.
Action:      none
Not quite sure why you're getting that error as your identifiers look ok to me.
However, I would question a couple of things in your query...
e.g. the following types of statements do nothing...
nvl(LGUNAME,'')because an empty string is NULL, so you're just saying "if it's null then make it null"
Also, rownum is a number so:
ROWNUM='1'should be:
ROWNUM=1Don't make oracle have to do extra work by implicitly converting values.