Regular Expression Abbreviation of Words

Question

Suppose I have got data in my column like
Balla Ram Chog Mal College
Maharishi Dayanand University
Cambridge Public School
Now I want to write a query using regular expressions to find out the abbreviations. e.g the resulting data set should be:
BRCMC
MDU
CPS
How should I write regexp for it ?

Answer 1

One way, using SUBSTR and INSTR, tested on 10g.
with data as
  select 'Balla Ram Chog Mal College' col from dual union all
  select 'Maharishi Dayanand University' col from dual union all
  select 'Cambridge Public School' col from dual
select col, replace(ltrim(max(sys_connect_by_path(str, ',')) keep (dense_rank last order by r), ','), ',') abbr
  from (
select col, substr(col, decode(level, 1, 1, instr(col, ' ', 1, level - 1) + 1), 1) str, level, row_number() over (partition by col order by level) r
  from data
connect by level <= length(col) - length(replace(col, ' ')) + 1
       and col = prior col
       and prior sys_guid() is not null
order by col, level
group by col
start with r = 1
connect by r - 1 = prior r
       and col = prior col
       and prior sys_guid() is not null;
COL                           ABBR
Balla Ram Chog Mal College    BRCMC
Cambridge Public School       CPS 
Maharishi Dayanand University MDU
With 11g, you will not require the Outer query to concatenate the results, you can directly use LISTAGG as demonstrated by Hashim.