Never add a RETURN clause before closing the cursor.
In the exception-handling block, always check to see whether explicit cursors are open, and if so, close them.
Forgotten cursors that are left open can bring a system to a halt.
SQL>
SQL> -- create demo table
SQL> create table Employee(
2 ID VARCHAR2(4 BYTE) NOT NULL,
3 First_Name VARCHAR2(10 BYTE),
4 Last_Name VARCHAR2(10 BYTE),
5 Start_Date DATE,
6 End_Date DATE,
7 Salary Number(8,2),
8 City VARCHAR2(10 BYTE),
9 Description VARCHAR2(15 BYTE)
10 )
11 /
Table created.
SQL>
SQL> -- prepare data
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values ('01','Jason', 'Martin', to_date('19960725','YYYYMMDD'), to_date('20060725','YYYYMMDD'), 1234.56, 'Toronto', 'Programmer')
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('02','Alison', 'Mathews', to_date('19760321','YYYYMMDD'), to_date('19860221','YYYYMMDD'), 6661.78, 'Vancouver','Tester')
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('03','James', 'Smith', to_date('19781212','YYYYMMDD'), to_date('19900315','YYYYMMDD'), 6544.78, 'Vancouver','Tester')
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('04','Celia', 'Rice', to_date('19821024','YYYYMMDD'), to_date('19990421','YYYYMMDD'), 2344.78, 'Vancouver','Manager')
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('05','Robert', 'Black', to_date('19840115','YYYYMMDD'), to_date('19980808','YYYYMMDD'), 2334.78, 'Vancouver','Tester')
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('06','Linda', 'Green', to_date('19870730','YYYYMMDD'), to_date('19960104','YYYYMMDD'), 4322.78,'New York', 'Tester')
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('07','David', 'Larry', to_date('19901231','YYYYMMDD'), to_date('19980212','YYYYMMDD'), 7897.78,'New York', 'Manager')
3 /
1 row created.
SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values('08','James', 'Cat', to_date('19960917','YYYYMMDD'), to_date('20020415','YYYYMMDD'), 1232.78,'Vancouver', 'Tester')
3 /
1 row created.
SQL>
SQL> -- display data in the table
SQL> select * from Employee
2 /
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
---- ---------- ---------- --------- --------- ---------- ---------- ---------------
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer
02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester
03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester
04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager
05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester
06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester
07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager
08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester
8 rows selected.
SQL>
SQL> create or replace function f_getList_tx
2 (i_source_tx VARCHAR2,
3 i_column_tx VARCHAR2,
4 i_filter_tx VARCHAR2,
5 i_separator_tx VARCHAR2)
6 return VARCHAR2
7 is
8 v_string_tx VARCHAR2(4000);
9 v_temp_tx VARCHAR2(4000);
10 v_out_tx VARCHAR2(4000);
11 v_weak_ref sys_refcursor;
12 begin
13 v_string_tx:='select '||i_column_tx||
14 ' from '||i_source_tx||
15 ' where '||i_filter_tx;
16 open v_weak_ref for v_string_tx;
17 loop
18 fetch v_weak_ref into v_temp_tx;
19 exit when v_weak_ref%NOTFOUND;
20
21 if v_out_tx is null then
22 v_out_tx:=v_temp_tx;
23 else
24 v_out_tx:=v_out_tx||i_separator_tx||v_temp_tx;
25 end if;
26 end loop;
27
28 close v_weak_ref;
29 return v_out_tx;
30 exception
31 when others then
32 if v_weak_ref%isOpen then
33 close v_weak_ref;
34 raise;
35 end if;
36 end;
37 /
Function created.
SQL> select f_getList_tx('employee','first_name','salary > 200',',') from dual;
F_GETLIST_TX('EMPLOYEE','FIRST_NAME','SALARY>200',',')
--------------------------------------------------------
Jason,Alison,James,Celia,Robert,Linda,David,James
SQL>
SQL> -- clean the table
SQL> drop table Employee
2 /
Table dropped.
SQL>