regex - Regular Expression - Get specific group value in SQL -

i have following regular expression problem.

input:

123_321_009 3111_00_001 5123_123 555 666_a66 777_b77_777 

output request below:

123_321 3111_00 5123 555 666_a66 777_b77 

is there way value of output above?

i tried below statement lack idea how value needed.

^(.*?)\\s?([_0-9])?$ 

value appearing after last underscore not needed.

since using oracle, can use regex_replace(val,pattern,'') function pattern.

the following patterns satisfy samples provided:

_[0-9]{3}$

_[0-9]*$

here demonstration of approach using sql*plus:

 scott@dev> tab(num_val)       2    ( select '123_321_009' dual       3    union       4    select '3111_00_001' dual       5    union       6    select '5123_123' dual       7    union       8    select '555' dual       9    )      10  select tab.num_val,      11    regexp_replace(tab.num_val,'_[0-9]{3}$') approach_1,      12    regexp_replace(tab.num_val,'_[0-9]*$') approach_2      13  tab      14  /      num_val     approach_1             approach_2     =========== ====================== ==================     123_321_009 123_321                123_321     3111_00_001 3111_00                3111_00     5123_123    5123                   5123     555         555                    555 

if provided larger sampling (or more specific rule), more specific solution provided.