问题
I want to be able to split csv strings in Oracle 9i
I've read the following article http://www.oappssurd.com/2009/03/string-split-in-oracle.html
But I didn't understand how to make this work. Here are some of my questions pertaining to it
- Would this work in Oracle 9i, if not, why not?
- Is there a better way of going about splitting csv strings then the solution presented above?
- Do I need to create a new type? If so, do I need specific privilages for that?
- Can I declare the type w/in the function?
回答1:
Here's a string tokenizer for Oracle that's a little more straightforward than that page, but no idea if it's as fast:
create or replace function splitter_count(str in varchar2, delim in char) return int as
val int;
begin
val := length(replace(str, delim, delim || ' '));
return val - length(str);
end;
create type token_list is varray(100) of varchar2(200);
CREATE or replace function tokenize (str varchar2, delim char) return token_list as
ret token_list;
target int;
i int;
this_delim int;
last_delim int;
BEGIN
ret := token_list();
i := 1;
last_delim := 0;
target := splitter_count(str, delim);
while i <= target
loop
ret.extend();
this_delim := instr(str, delim, 1, i);
ret(i):= substr(str, last_delim + 1, this_delim - last_delim -1);
i := i + 1;
last_delim := this_delim;
end loop;
ret.extend();
ret(i):= substr(str, last_delim + 1);
return ret;
end;
You can use it like this:
select tokenize('hi you person', ' ') from dual;
VARCHAR(hi,you,person)
回答2:
Joyce,
Here are three examples:
1) Using dbms_utility.comma_to_table. This is not a general purpose routine, because the elements should be valid identifiers. With some dirty tricks we can make it work more universal:
SQL> declare
2 cn_non_occuring_prefix constant varchar2(4) := 'zzzz';
3 mystring varchar2(2000):='a:sd:dfg:31456:dasd: :sdfsdf'; -- just an example
4 l_tablen binary_integer;
5 l_tab dbms_utility.uncl_array;
6 begin
7 dbms_utility.comma_to_table
8 ( list => cn_non_occuring_prefix || replace(mystring,':',','||cn_non_occuring_prefix)
9 , tablen => l_tablen
10 , tab => l_tab
11 );
12 for i in 1..l_tablen
13 loop
14 dbms_output.put_line(substr(l_tab(i),1+length(cn_non_occuring_prefix)));
15 end loop;
16 end;
17 /
a
sd
dfg
31456
dasd
sdfsdf
PL/SQL-procedure is geslaagd.
2) Using SQL's connect by level. If you are on 10g or higher you can use the connect-by-level approach in combination with regular expressions, like this:
SQL> declare
2 mystring varchar2(2000):='a:sd:dfg:31456:dasd: :sdfsdf'; -- just an example
3 begin
4 for r in
5 ( select regexp_substr(mystring,'[^:]+',1,level) element
6 from dual
7 connect by level <= length(regexp_replace(mystring,'[^:]+')) + 1
8 )
9 loop
10 dbms_output.put_line(r.element);
11 end loop;
12 end;
13 /
a
sd
dfg
31456
dasd
sdfsdf
PL/SQL-procedure is geslaagd.
3) Again using SQL's connect by level, but now in combination with good old SUBSTR/INSTR in case you are on version 9, like you are:
SQL> declare
2 mystring varchar2(2000):='a:sd:dfg:31456:dasd: :sdfsdf'; -- just an example
3 begin
4 for r in
5 ( select substr
6 ( str
7 , instr(str,':',1,level) + 1
8 , instr(str,':',1,level+1) - instr(str,':',1,level) - 1
9 ) element
10 from (select ':' || mystring || ':' str from dual)
11 connect by level <= length(str) - length(replace(str,':')) - 1
12 )
13 loop
14 dbms_output.put_line(r.element);
15 end loop;
16 end;
17 /
a
sd
dfg
31456
dasd
sdfsdf
PL/SQL-procedure is geslaagd.
You can see some more techniques like these, in this blogpost: http://rwijk.blogspot.com/2007/11/interval-based-row-generation.html
Hope this helps.
Regards, Rob.
To address your comment:
An example of inserting the separated values into a normalized table.
First create the tables:
SQL> create table csv_table (col)
2 as
3 select 'a,sd,dfg,31456,dasd,,sdfsdf' from dual union all
4 select 'a,bb,ccc,dddd' from dual union all
5 select 'zz,yy,' from dual
6 /
Table created.
SQL> create table normalized_table (value varchar2(10))
2 /
Table created.
Because you seem interested in the dbms_utility.comma_to_table approach, I mention it here. However, I certainly do not recommend this variant, because of the identifier quirks and because of the slow row by row processing.
SQL> declare
2 cn_non_occuring_prefix constant varchar2(4) := 'zzzz';
3 l_tablen binary_integer;
4 l_tab dbms_utility.uncl_array;
5 begin
6 for r in (select col from csv_table)
7 loop
8 dbms_utility.comma_to_table
9 ( list => cn_non_occuring_prefix || replace(r.col,',',','||cn_non_occuring_prefix)
10 , tablen => l_tablen
11 , tab => l_tab
12 );
13 forall i in 1..l_tablen
14 insert into normalized_table (value)
15 values (substr(l_tab(i),length(cn_non_occuring_prefix)+1))
16 ;
17 end loop;
18 end;
19 /
PL/SQL procedure successfully completed.
SQL> select * from normalized_table
2 /
VALUE
----------
a
sd
dfg
31456
dasd
sdfsdf
a
bb
ccc
dddd
zz
yy
14 rows selected.
I do recommend this single SQL variant:
SQL> truncate table normalized_table
2 /
Table truncated.
SQL> insert into normalized_table (value)
2 select substr
3 ( col
4 , instr(col,',',1,l) + 1
5 , instr(col,',',1,l+1) - instr(col,',',1,l) - 1
6 )
7 from ( select ',' || col || ',' col from csv_table )
8 , ( select level l from dual connect by level <= 100 )
9 where l <= length(col) - length(replace(col,',')) - 1
10 /
14 rows created.
SQL> select * from normalized_table
2 /
VALUE
----------
a
a
zz
sd
bb
yy
dfg
ccc
31456
dddd
dasd
sdfsdf
14 rows selected.
Regards, Rob.
回答3:
You might want to be a bit clearer on what you want to do, then we can give you a specific answer. Showing some of your code is always helpful :)
If you are using paramters, to split a string of csv numbers (eg: 1,2,3,4) then use that in a IN statement have a look at the function str2tbl() in Question 670922. With a few changes you could change it to a VARCHAR2 or whatever you need.
In the following you could set :sMyCatagories equal to '1,2,3,4'
create or replace type myTableType as table of number;
create or replace function str2tbl( p_str in varchar2 ) return myTableType
as
l_str long default p_str || ',';
l_n number;
l_data myTableType := myTabletype();
begin
loop
l_n := instr( l_str, ',' );
exit when (nvl(l_n,0) = 0);
l_data.extend;
l_data( l_data.count ) := ltrim(rtrim(substr(l_str,1,l_n-1)));
l_str := substr( l_str, l_n+1 );
end loop;
return l_data;
end;
and using it in a select statement....
SELECT
*
FROM
atable a
WHERE
a.category in (
select * from INLIST (
select cast(str2tbl(:sMyCatagories) as mytableType) from dual
)
);
This is really only useful if you are using parameters. If you are munging together SQL in your application, then just use a normal IN statement.
SELECT
*
FROM
atable a
WHERE
a.category in (1,2,3,4);
回答4:
I used this in the end
create or replace function split
(
p_list varchar2
) return sys.dbms_debug_vc2coll pipelined
is
l_idx pls_integer;
l_list varchar2(32767) := p_list;
l_value varchar2(32767);
begin
loop
l_idx := instr(l_list,',');
if l_idx > 0 then
pipe row(substr(l_list,1,l_idx-1));
l_list := substr(l_list,l_idx+length(','));
else
pipe row(l_list);
exit;
end if;
end loop;
return;
end split;
declare
CURSOR c IS select occurrence_num, graphics from supp where graphics is not null and graphics not like ' %';
begin
FOR r IN c LOOP
insert into image (photo_id,report_id, filename)
select image_key_seq.nextval photo_id, r.occurrence_num report_id,
t.column_value filename from table(split(cast(r.graphics as varchar2(1000)))) t where t.column_value is not null;
END LOOP;
end ;
回答5:
It sounds like you don't want to add schema (types, function). One SQL only way to parse the delimited text is to 'go crazy' with instr and substr calls.
DECLARE
V_CSV_STRING VARCHAR2(100);
BEGIN
--Create a test delimited list of first_name, last_name, middle_init
V_CSV_STRING := 'Brian,Hart,M';
select substr( V_CSV_STRING||',', 1, instr(V_CSV_STRING,',')-1 ) FIRST_NAME,
substr( V_CSV_STRING||',,', instr( V_CSV_STRING||',,', ',') +1,
instr( V_CSV_STRING||',,', ',', 1, 2 )-instr(V_CSV_STRING||',,',',')-1 ) LAST_NAME,
rtrim(substr( V_CSV_STRING||',,', instr( V_CSV_STRING||',,',',',1,2)+1),',') MIDDLE_INIT
from dual;
END;
If your looking to formalize a structure and adding the appropriate application code (functions, views, types etc...) I would take a look at Tom Kyte's writing on this subject.
来源：https://stackoverflow.com/questions/1089508/how-to-best-split-csv-strings-in-oracle-9i