pl/sql procedure

By ukmodak | June 6th 2022 12:23:03 PM | viewed 8 times

Function VS Procedure:

Procedure:

procedure is a group of PL/SQL statements that can be called by name. The call specification (sometimes called call spec) specifies a java method or a third-generation language routine so that it can be called from SQL and PL/SQL.

The procedure contains a header and a body.

  • Header: The header contains the name of the procedure and the parameters or variables passed to the procedure.
  • Body: The body contains a declaration section, execution section and exception section similar to a general PL/SQL block.
How to pass parameters in procedure:

When you want to create a procedure or function, you have to define parameters .There is three ways to pass parameters in procedure:

  • IN: It is a default parameter. It passes the value to the subprogram.
  • OUT: It must be specified. It returns a value to the caller.
  • IN OUT: It must be specified. It passes an initial value to the subprogram and returns an updated value to the caller.
Sl No Function Procedure
1 A function has a return type and returns a value. A procedure does not have a return type. But it returns values using the OUT parameters.
2 You cannot use a function with Data Manipulation queries. Only Select queries are allowed in functions. You can use DML queries such as insert, update, select etc… with procedures.
3 A function does not allow output parameters A procedure allows both input and output parameters.
4 You cannot manage transactions inside a function. You can manage transactions inside a procedure..
5 You cannot call stored procedures from a function You can call a function from a stored procedure..
6 You can call a function using a select statement. You cannot call a procedure using select statements.
Procedure code :
create or replace procedure ddlUktable is
   ddl_qry varchar2(4000);
begin
   ddl_qry := 'CREATE TABLE UKACCOUNT.uktable(
                id     NUMBER(3),
                name    VARCHAR2(50)
				primary key(id)
                )';
    EXECUTE IMMEDIATE ddl_qry;
end ddlUktable;
CREATE OR REPLACE Procedure UpdateCourse
   ( name_in IN varchar2 )

IS
   cnumber number;

   cursor c1 is
   SELECT course_number
    FROM courses_tbl
    WHERE course_name = name_in;

BEGIN

   open c1;
   fetch c1 into cnumber;

   if c1%notfound then
      cnumber := 9999;
   end if;

   INSERT INTO student_courses
   ( course_name,
     course_number )
   VALUES
   ( name_in,
     cnumber );

   commit;

   close c1;

EXCEPTION
WHEN OTHERS THEN
   raise_application_error(-20001,'An error was encountered - '||SQLCODE||' -ERROR- '||SQLERRM);
END;

Row query parsing in pl/sql using procedure

create or replace procedure VerifyQuerySyntax(p_query in clob, isvalid out integer) is  
c number;  
BEGIN  
c := DBMS_SQL.OPEN_CURSOR;  
DBMS_SQL.PARSE (c, p_query, DBMS_SQL.Native);  
DBMS_SQL.CLOSE_CURSOR (c);  
DBMS_OUTPUT.put_line('Correct' );  
isvalid:=1;  
--Statement parsed successfully  
EXCEPTION  
WHEN OTHERS THEN  
--statement invalid  
DBMS_OUTPUT.put_line('Error : ' || Sqlcode||' - '|| sqlerrm );  
DBMS_SQL.CLOSE_CURSOR(c);  
isvalid:=0;  
  
END VerifyQuerySyntax; 
/

Declare  
isValid integer;  
query varchar2(32767) := 'SELECT * FROM Customer';  
Begin  
VerifyQuerySyntax(query , isValid );  
dbms_output.put_line( 'isValid : '||isValid );  
End;
/

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