Exact difference between function and procedure

Question

exact difference between function and procedure(real time diff.....not like return value, dml....) and function do some work at the same time that work also do procedure..why function

Answer 1

ranitB wrote:
1. Function is called Inline a query. A return value is must.
But, procedure may/may not contain a return value.Not true.
A function may be called in a query providing it meets certain limitations (no DDL, or transactional statements such as commit/rollback etc.).
A function does not have to be called from a query, it can be called from other PL/SQL code or from other external applications.
Regular functions must return a value, though pipelined functions do not...
SQL> CREATE OR REPLACE TYPE split_tbl IS TABLE OF VARCHAR2(32767);
  2  /
Type created.
SQL> CREATE OR REPLACE FUNCTION split (p_list VARCHAR2, p_delim VARCHAR2:=' ') RETURN SPLIT_TBL PIPELINED IS
  2      l_idx    PLS_INTEGER;
  3      l_list   VARCHAR2(32767) := p_list;
  4      l_value  VARCHAR2(32767);
  5    BEGIN
  6      LOOP
  7        l_idx := INSTR(l_list, p_delim);
  8        IF l_idx > 0 THEN
  9          PIPE ROW(SUBSTR(l_list, 1, l_idx-1));
10          l_list := SUBSTR(l_list, l_idx+LENGTH(p_delim));
11        ELSE
12          PIPE ROW(l_list);
13          EXIT;
14        END IF;
15      END LOOP;
16      RETURN;
17    END SPLIT;
18  /
Function created.
SQL> SELECT column_value
  2  FROM TABLE(split('FRED,JIM,BOB,TED,MARK',','));
COLUMN_VALUE
FRED
JIM
BOB
TED
MARK... whilst the definition of the function shows a return type, the return statement inside the function simply returns, without a value. That's because the data is passed back through a special "pipeline", and you can write code to show that the data is available to a query as soon as it's piped, and before the function has completed (reached the return statement) if you like.
A procedure does not return a value (And no an OUT parameter is not a "returned" value, it's a writeable parameter, there's a difference)
2. There are some limitations in functions which is possbl through procedures.
Like - Oracle doesn't support DML in functions called in Select queries (using PRAGMA AUTONOMOUS_TRANSACTION will help).Not strictly true. and SQL query is considered to be DML, so a function could perform a query and then be used inside another query...
SQL> ed
Wrote file afiedt.buf
  1  create or replace function f_dname(p_deptno in number) return varchar2 is
  2    v_dname varchar2(10);
  3  begin
  4    select dname into v_dname
  5    from   dept
  6    where  deptno = p_deptno;
  7    return v_dname;
  8* end;
SQL> /
Function created.
SQL> ed
Wrote file afiedt.buf
  1* select empno, ename, f_dname(deptno) as dname from emp
SQL> /
     EMPNO ENAME      DNAME
      7369 SMITH      RESEARCH
      7499 ALLEN      SALES
      7521 WARD       SALES
      7566 JONES      RESEARCH
      7654 MARTIN     SALES
      7698 BLAKE      SALES
      7782 CLARK      ACCOUNTING
      7788 SCOTT      RESEARCH
      7839 KING       ACCOUNTING
      7844 TURNER     SALES
      7876 ADAMS      RESEARCH
      7900 JAMES      SALES
      7902 FORD       RESEARCH
      7934 MILLER     ACCOUNTING
14 rows selected.It's been discussed many times on the forum... my favourite here...
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Edited by: BluShadow on 17-Sep-2012 09:22