Evaluating an expression stored as varchar

Hi,
I've declared a varchar variable and the data stored in that variable is an expression.
I need to evaluate the expression.
Is there any option to do so.
For example
v_s_expression:='10+5';
i need to evaluate and get the value into another variable.
i should get the result 15 in the variable v_n_result.
any methods?
Thanks in advance
Prasanth

first of all why?....
execute immediate 'select '||v_s_expression||' from dual' into res;like in
SQL> declare
2     v_s_expression varchar2(10);
3     res number;
4 begin
5     v_s_expression:='10+5';
6     execute immediate 'select '||v_s_expression||' from dual' into res;
7     dbms_output.put_line(res);
8 end;
9 /
15
PL/SQL procedure successfully completed.

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DATA: sum         TYPE i,
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Message was edited by: Sam

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user530956 wrote:
I have noticed in one of application, all date timestamp columns has been stored in Varchar. If i convert those date columns into timestamp datatype, will it again any performance in select queries?
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<employeeid>1122</employeeid>
<employeename>challa</employeename>
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<managerempid>232</managerempid>
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<employeeid>1123</employeeid>
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TableX
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Matthew:
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SQL> CREATE OR REPLACE FUNCTION my_eval (
2     p_tab_name IN VARCHAR2,
3     p_rowid IN ROWID,
4     p_calc_col IN VARCHAR2) RETURN NUMBER IS
5
6 sqlstr VARCHAR2(4000);
7 result NUMBER;
8 BEGIN
9     sqlstr:= 'SELECT '||p_calc_col||' FROM '||p_tab_name||' WHERE rowid = :b';
10     EXECUTE IMMEDIATE sqlstr INTO result USING p_rowid;
11     RETURN result;
12 END;
13 /
Function created.
SQL> CREATE TABLE jtest (col1 number,col2 number,col3 varchar2(50));
Table created.
SQL> INSERT INTO jtest values (5, 7, 'Col1+Col2');
1 row created.
SQL> INSERT INTO jtest values (10, 3, 'Col1*Col2');
1 row created.
SQL> INSERT INTO jtest values (20, 5, 'Col1/Col2');
1 row created.
SQL> commit;
Commit complete.
SQL> SELECT col1,col2,col3,MY_EVAL('jtest',rowid,col3) evald
2 FROM jtest
3 /
      COL1       COL2 COL3                           EVALD
         5          7 Col1+Col2                         12
        10          3 Col1*Col2                         30
        20          5 Col1/Col2                          4
SQL> DROP TABLE jtest;
Table dropped.
SQL> CREATE TABLE jtest (col1 number,col2 number,col3 number,col4 varchar2(50));
Table created.
SQL> INSERT INTO jtest values (5, 7, 2, '(Col1+Col2)/Col3');
1 row created.
SQL> INSERT INTO jtest values (10, 3, 5, 'Col1*(Col2+Col3)');
1 row created.
SQL> INSERT INTO jtest values (20, 5, 2, 'Col1/Col2/Col3');
1 row created.
SQL> commit;
Commit complete.
SQL> SELECT col1,col2,col3,col4,MY_EVAL('jtest',rowid,col4) evald
2 FROM jtest;
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         5          7          2 (Col1+Col2)/Col3                   6
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John

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Hi,
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06:26:00   2     RETURN NUMBER
06:26:00   3 IS
06:26:00   4     l_dual_record   DUAL%ROWTYPE;
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06:26:00   9
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06:26:00 11
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06:26:00 13     THEN
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06:26:00 15     ELSE
06:26:00 16        l_this_result := 0;
06:26:00 17     END IF;
06:26:00 18
06:26:00 19     CLOSE csr_dual;
06:26:00 20
06:26:00 21     RETURN l_this_result;
06:26:00 22 END;
06:26:00 23 /
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Elapsed: 00:00:00.02
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Does anyone have a suggestion for another approach?I don't think you'll gain any performance but for the records:
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I can't count how many times this has been askedhere.
Try searching the forums.Give yourself credit - you could count it if you
wanted to.
OK, maybe so. But I can't count it off the top of my
head. :-) But easier than counting the hairs on your head (well.....presuming you do have some....)
Really, it's bizarre how much this gets
asked. I think I'll start a new thread about it...Be realistic....the integer to string or string to integer gets asked a lot more often!

Evaluating an expression stored as varchar

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