如有空格，如何将NAME分为3个不同的字段FIRST_NAME，MIDDLE_NAME和LAST_NAME

Question

How to split NAME into 3 different fields FIRST_NAME, MIDDLE_NAME & LAST_NAME .

Currently the NAME filed is in the following format [FIRST_NAME || ' ' || MIDDLE_NAME|| ' ' ||LAST_NAME] [FIRST_NAME || ' ' || MIDDLE_NAME|| ' ' ||LAST_NAME] [FIRST_NAME || ' ' || MIDDLE_NAME|| ' ' ||LAST_NAME] . To be more clear suppose a person name is

FIRST_NAME: SHERRY 
MIDDLE_NAME: L
LAST_NAME : CLEAVES

then the NAME field has "SHERRY L CLEAVES", I want it in 3 different fields. Also, How do I handle if there are only two names?

some of the sample data as follows:

  ('William  Sears',
       'PETER E LABBE',
       'Edith  Roberts',
       'SHERRY L CLEAVES',
       'Sharon  Matthes',
       'TAMMY L PELLETIER',
       'STACIE M KINER',
       'MICHAEL C THOMAS',
       'CHESTER R DAVIS',
       'MICHAEL D HUTCHINSON',
       'Paul  Mikkelsen'
       )

Answer 1

Here's one way to do it:

with data_qry
as
(
select 'William  Sears' as name from dual union all
select 'PETER E LABBE' as name from dual union all
select 'Edith  Roberts' as name from dual union all
select 'SHERRY L CLEAVES' as name from dual union all
select 'Sharon  Matthes' as name from dual union all
select 'TAMMY L PELLETIER' as name from dual union all
select 'STACIE M KINER' as name from dual union all
select 'MICHAEL C THOMAS' as name from dual union all
select 'CHESTER R DAVIS' as name from dual union all
select 'MICHAEL D HUTCHINSON' as name from dual union all
select 'Paul  Mikkelsen' as name from dual
)
select name
     , substr(name, 1, instr(name, ' ', 1)) as first
     , case when instr(name, ' ', 1, 2) > 0 then substr(name, instr(name, ' ', 1, 1) + 1, instr(name, ' ', 1, 2) - instr(name, ' ', 1, 1) - 1) else null end as middle
     , case when instr(name, ' ', 1, 2) > 0 then substr(name, instr(name, ' ', 1, 2) + 1) else substr(name, instr(name, ' ', 1, 1) + 1) end as last
from data_qry

Output:

NAME                 FIRST      MIDDLE     LAST
William  Sears       William               Sears
PETER E LABBE        PETER      E          LABBE
Edith  Roberts       Edith                 Roberts
SHERRY L CLEAVES     SHERRY     L          CLEAVES
Sharon  Matthes      Sharon                Matthes
TAMMY L PELLETIER    TAMMY      L          PELLETIER
STACIE M KINER       STACIE     M          KINER
MICHAEL C THOMAS     MICHAEL    C          THOMAS
CHESTER R DAVIS      CHESTER    R          DAVIS
MICHAEL D HUTCHINSON MICHAEL    D          HUTCHINSON
Paul  Mikkelsen      Paul                  Mikkelsen

Answer 2

You could do something like this. I took care of a few possibilities, like an arbitrary number of spaces between first and last name (no middle initial) or between first name and initial, or between initial and last name. Also multi-letter initials. There will still be plenty of other, unanticipated problems, like people with two first names or two last names, etc.

with input_strings ( str ) as (
       select 'William  Sears'       from dual union all
       select 'PETER E LABBE'        from dual union all
       select 'Edith  Roberts'       from dual union all
       select 'SHERRY L CLEAVES'     from dual union all
       select 'Sharon  Matthes'      from dual union all
       select 'TAMMY L PELLETIER'    from dual union all
       select 'STACIE M KINER'       from dual union all
       select 'MICHAEL C THOMAS'     from dual union all
       select 'CHESTER R DAVIS'      from dual union all
       select 'MICHAEL D HUTCHINSON' from dual union all
       select 'Paul  Mikkelsen'      from dual
     )
select initcap(substr(str, 1, instr(str, ' ') - 1)) as first_name,
       upper(trim(substr(str, instr(str, ' '), 
               instr(str, ' ', -1) - instr(str, ' ')))) as mid_in,
       initcap(substr(str, instr(str, ' ', -1) + 1)) as last_name
from   input_strings;

FIRST_NAME                     MID_IN LAST_NAME
------------------------------ ------ ------------------------------
William                               Sears
Peter                          E      Labbe
Edith                                 Roberts
Sherry                         L      Cleaves
Sharon                                Matthes
Tammy                          L      Pelletier
Stacie                         M      Kiner
Michael                        C      Thomas
Chester                        R      Davis
Michael                        D      Hutchinson
Paul                                  Mikkelsen

11 rows selected.

Answer 3

Hey don't forget regular expressions! Assuming your (really too simple for names) given specs for names which assume a space for a delimiter, and the fact you are not dealing with the usual name issues, this is really just parsing a delimited string which can be done with a regex that can handle NULL list elements (the middle initial):

SQL> with tbl(name) as (
   select 'William  Sears'       from dual union all
   select 'PETER E LABBE'        from dual union all
   select 'Edith  Roberts'       from dual union all
   select 'SHERRY L CLEAVES'     from dual union all
   select 'Sharon  Matthes'      from dual union all
   select 'TAMMY L PELLETIER'    from dual union all
   select 'STACIE M KINER'       from dual union all
   select 'MICHAEL C THOMAS'     from dual union all
   select 'CHESTER R DAVIS'      from dual union all
   select 'MICHAEL D HUTCHINSON' from dual union all
   select 'Paul  Mikkelsen'      from dual
   )
   select regexp_substr(name, '(.*?)( |$)', 1, 1, NULL, 1) first_name,
          regexp_substr(name, '(.*?)( |$)', 1, 2, NULL, 1) mid_init,
          regexp_substr(name, '(.*?)( |$)', 1, 3, NULL, 1) last_name
   from tbl;

FIRST_NAME           MID_INIT             LAST_NAME
-------------------- -------------------- --------------------
William                                   Sears
PETER                E                    LABBE
Edith                                     Roberts
SHERRY               L                    CLEAVES
Sharon                                    Matthes
TAMMY                L                    PELLETIER
STACIE               M                    KINER
MICHAEL              C                    THOMAS
CHESTER              R                    DAVIS
MICHAEL              D                    HUTCHINSON
Paul                                      Mikkelsen

11 rows selected.

SQL>

Yes, it's been said a million times but I'll save you the trouble: substr()/instr() is faster but I find the nested substr()/instr() syntax more ghastly than the ghastly regex syntax. I'm probably in the minority. Flame away anyway, you know you can't help yourself! :-)