Why am i getting rows which are equal?

Question

Hi All,
  why am I getting the values which are equal(highlighted in bold letters) even though I  have a greater than condition(bold letters) in the where clause of the below query?
     select name1, name2,
       length(ltrim(rtrim(name2))) length_unit,length(ltrim(rtrim(name1))) length_name1 from ucbprem
where ltrim(rtrim(name1)) != ltrim(rtrim(name2))
  and length(ltrim(rtrim(name2))) > length(ltrim(rtrim(name1)))
  and instr(ltrim(rtrim(name2)),' ') !=0
  and substr(ltrim(rtrim(name2)),1,instr(name2,' ')-1) = ltrim(rtrim(name1)) OR substr(ltrim(rtrim(name2)),1,instr(name2,' ')-1) = substr(ltrim(rtrim(name1)),1,2)
order by name1, name2;
name1 name2   length_name2    length_name1
BLDG   BLDG F           6               4
BLDG   BLDG G           6               4
BLDG   BLDG H           6               4
BLDG   BLDG H           6               4
BLDG   BLDG I           6               4
BLDG   BLDG J           6               4
BLDG   BLDG R           6               4
BLDG   BLDG W           6               4
FRNT FR 2 4 4
FRNT FR A 4 4
LOWR LO A 4 4
REAR RE 2 4 4
REAR RE 2 4 4
REAR RE A 4 4
REAR RE B 4 4
REAR RE B 4 4
REAR RE C 4 4
REAR RE D 4 4
UPPR   UP 2M            5               4
Any idea?
Thanks in advance
R.R

Answer 1

OR substr(ltrim(rtrim(name2)),1,instr(name2,' ')-1) = substr(ltrim(rtrim(name1)),1,2)
SQL> conn scott/tiger
Connected.
SQL> create table trimm (name1 varchar2(4), name2 varchar2(4));
Table created.
SQL> insert into trimm values ('FRNT', 'FR 2');
1 row created.
SQL> select * from trimm
  2  where substr(ltrim(rtrim(name2)),1,instr(name2,' ')-1) = substr(ltrim(rtrim(name1)),1,2);
NAME NAME
FRNT FR 2Message was edited by:
stevencallan