String Split
On occasion we need split and treat a single comma-delimited value as if it were a column in a table. There are two methods to achieve this.
1.TABLE SQL function
We can take advantage of the TABLE SQL function and PL/SQL function to do this.
Example:
CREATE OR REPLACE TYPE GTYP_STR_TABLE IS TABLE OF VARCHAR2 (32767);
/
CREATE OR REPLACE FUNCTION split(pv_list VARCHAR2, pv_del VARCHAR2 := ',')
RETURN gtyp_str_table
PIPELINED IS
lv_idx PLS_INTEGER;
lv_list VARCHAR2(32767) := pv_list;
lv_value VARCHAR2(32767);
BEGIN
LOOP
lv_idx := instr(lv_list, pv_del);
IF lv_idx > 0
THEN
PIPE ROW(substr(lv_list, 1, lv_idx - 1));
lv_list := substr(lv_list, lv_idx + length(pv_del));
ELSE
PIPE ROW(lv_list);
EXIT;
END IF;
END LOOP;
RETURN;
END split;
/
With this function, we can run a query like this:
select * from table(split('a,b,c'));
2. Regular expression function
On occasion that customized functions can’t be used, we can use regexp_substr to archive this.
Example:
The example table description as below:
SQL> desc table2;
Name Type Nullable Default Comments
--------- ------------- -------- ------- --------
ID NUMBER(20) Y
NAMES VARCHAR2(100) Y
SQL> select * from table2;
ID NAMES
--------------------- --------------------------------------------------------------------------------
1 name1,name2
2 name2,name3
String split Sql is:
SQL> SELECT NAME, id
FROM (SELECT regexp_substr(t2.names, '[^,]+', 1, LEVEL) NAME,
LEVEL lv,
lag(LEVEL, 1, 0) over(PARTITION BY t2.id ORDER BY LEVEL) lg,
t2.id
FROM table2 t2
CONNECT BY regexp_substr(t2.names, '[^,]+', 1, LEVEL) IS NOT NULL)
WHERE lv != lg;
The result is:
NAME ID
---------
name1 1
name2 1
name2 2
name3 2
reference:
http://articles.techrepublic.com.com/5100-10878_11-5259821.html
http://www.oracle.com/technology/oramag/code/tips2007/070907.html