DML in functions is causing problem.

Question

I have a function as below which is called from a number of procedures and triggers. It just returns the next unique row number in a table for a particular session.
>>>>>>>>>>>>>>>
CREATE OR REPLACE FUNCTION "SPR_MAX_VALUE" (tname VARCHAR2,sessn_id NUMBER)
return NUMBER AS
V_CURSOR BINARY_INTEGER;
SL_TAB_STMT VARCHAR2(200);
V_RETURN_CODE binary_INTEGER;
SLNO NUMBER(10);
SL_NO NUMBER(10);
BEGIN
DBMS_OUTPUT.PUT_LINE('VALUE OF EMP CODE BEGIN');
SL_TAB_STMT:='BEGIN SELECT MAX_SLNO ' ||' INTO '|| ':SLNO' ||
' FROM TEMP_IDENTITY WHERE SESSION_ID='|| SESSN_ID || ' AND TAB_NAME =''' || ltrim(rtrim(TNAME)) || '''; END;';
DBMS_OUTPUT.PUT_LINE (SL_TAB_STMT);
V_CURSOR:= DBMS_SQL.OPEN_CURSOR;
DBMS_SQL.PARSE(V_CURSOR,SL_TAB_STMT,DBMS_SQL.NATIVE);
DBMS_SQL.BIND_VARIABLE(V_CURSOR,':SLNO',SL_NO);
V_RETURN_CODE:=DBMS_SQL.EXECUTE(V_CURSOR);
DBMS_SQL.VARIABLE_VALUE(V_CURSOR,':SLNO',SL_NO);
SL_NO:=SL_NO+1;
UPDATE TEMP_IDENTITY SET MAX_SLNO =SPR_MAX_VALUE.SL_NO WHERE TAB_NAME=SPR_MAX_VALUE.TNAME AND SESSION_ID=SPR_MAX_VALUE.SESSN_ID;
DBMS_OUTPUT.PUT_LINE('VALUE OF EMP CODE'|| SL_NO||' tNAME'||TNAME||' SESSION '||SESSN_ID);
DBMS_SQL.CLOSE_CURSOR(V_CURSOR);
RETURN SL_NO;
EXCEPTION
WHEN TOO_MANY_ROWS THEN
DBMS_OUTPUT.PUT_LINE ('TOO MANY ROWS RETRIVED');
DBMS_SQL.CLOSE_CURSOR(V_CURSOR);
WHEN NO_DATA_FOUND THEN
DBMS_SQL.CLOSE_CURSOR(V_CURSOR);
     SL_NO:=1;
INSERT INTO TEMP_IDENTITY VALUES(ltrim(rtrim(TNAME)),SL_NO,SESSN_ID);
RETURN SL_NO;
WHEN OTHERS THEN
DBMS_OUTPUT.PUT_LINE ('TOO MANY ROWS RETRIVED');
DBMS_SQL.CLOSE_CURSOR(V_CURSOR);
END;
<<<<<<<<<<
Below is the DML which is calling the above function
>>>>>>>>>>>>>
INSERT INTO tempp
SELECT spr_max_value('TEMPP ',sessnid),emp_code,status, effective_date "from_date", category, ( basic_pay + personal_pay
          + special_pay + stagnation_increment ), a.loc_code, b.ne_allow,
          b.assam_allow, b.hill_allow, b.portblair_allow, b.nagaland_allow,
          b.sikkim_allow, 0 "kargil_allow", b.hardship_allow, 0 "maxdate_bit",
          0 "adj0_bit", 0 "adj1_bit", 0 "exist_bit", 0 "old_amt", 0
          "new_amt", 0 "adj0_amt", 0 "adj1_amt", effective_yymm, NULL
          "to_date", 0 "no_days_in_mth", 0 "no_days",sessnid
     FROM HIST_EMPLOYEE a,MST_LOCATION b
     WHERE a.effective_yymm =200711
     and a.loc_code = b.loc_code
     and a.emp_code IN (
                         SELECT emp_code
                         FROM NAGALANDALLOW_TEMP_COUNT
                         WHERE session_id=sessnid
     order by emp_code;
<<<<<<<<<<<<<<
The problem I am facing is that ,the function spr_max_value('TEMPP ',sessnid) in the above DML is returning same value for all the rows even though logically it seems it should return unique numbers. It seems the update statement statement within the function is not working as I am expecting.
Can anyone help me out.

Answer 1

You are very much correct in the sense that the above
function is being used for maintaining manual indexes
and I very agree with you that the present design is
not a good one but immediately I won't be able to
change the same due to exigency and volume of
modifications required.
The DML is being used inside procedures and it is not
giving any error.
Is there any other way out.Nope. Which is an excellent excuse to fix it.