Re: How to write a SELECT stored procedure ?

From: Thomas Kyte <tkyte_at_us.oracle.com>
Date: Tue, 03 Aug 1999 15:33:59 GMT
Message-ID: <37aa0aca.8406097@newshost.us.oracle.com>

A copy of this was sent to tjmxyz_at_my-deja.com (if that email address didn't require changing) On Tue, 03 Aug 1999 09:23:40 GMT, you wrote:

>
>> Use cursor.
>> create or replace procedure GetNames()
>> begin
>> open mycursor for
>> select name from tbemployee;
>> end ;
>
>That will do nothing....
>Plus it wouldn't compile.
>

well, true, as written it is missing:

create or replace procedures GetNames( mycursor in out some_pkg.some_type ) as
begin

   open mycursor for select name from tbemployee; end;

it was missing the parameter declare and an "as".

>I think what you want is.
>To execute the stored procedure and retireve the rows
>on the client side.
>
>Just use:
>select name from tbemployee
>
>there is no advantage to having it as a stored procedure
>that I can think of.
>

well, there are a couple

• encapsulation, find a bug, fix the procedure and leave the code alone.
• implement complex logic in the server, eg: if ( user = 'BOB' ) then open mycursor for select a, b, SALARY from emp; else open mycursor for select a, b, to_number(null) salary from emp; end if;
• hiding the tables -- procedures run with the privs of the owner (can run with invokers rights in 8i as well). Therefore, I can open a cursor in a procedure for someone who could not open the cursor directly. They must call my api to get data from the database --a select will not work for them as they haven't been granted select....

are a few...

>The probelm is proecdure won't return the results
>into a cursor or record set.
>

With 7.2 on up of the database you have cursor variables. Cursor variables are cursors opened by a pl/sql routine and fetched from by another application or pl/sql routine (in 7.3 pl/sql routines can fetch from cursor variables as well as open them). The cursor variables are opened with the privelegs of the owner of the procedure and behave just like they were completely contained within the pl/sql routine. It uses the inputs to decide what database it will run a query on.

Here is an example:

create or replace package types
as

    type cursorType is ref cursor;
end;
/  

create or replace function sp_ListEmp return types.cursortype as

    l_cursor types.cursorType;
begin

    open l_cursor for select ename, empno from emp order by ename;  

    return l_cursor;
end;
/    

REM SQL*Plus commands to use a cursor variable  

variable c refcursor
exec :c := sp_ListEmp
print c

---

and the Pro*c to use this would look like:

static void process()
{
EXEC SQL BEGIN DECLARE SECTION;
    SQL_CURSOR my_cursor;

    VARCHAR     ename[40];
    int         empno;

EXEC SQL END DECLARE SECTION;       EXEC SQL WHENEVER SQLERROR DO sqlerror_hard();  

    EXEC SQL ALLOCATE :my_cursor;  

    EXEC SQL EXECUTE BEGIN
        :my_cursor := sp_listEmp;
    END; END-EXEC;       for( ;; )
    {

        EXEC SQL WHENEVER NOTFOUND DO break;
        EXEC SQL FETCH :my_cursor INTO :ename, empno;
 
        printf( "'%.*s', %d\n", ename.len, ename.arr, empno );

    }
    EXEC SQL CLOSE :my_cursor;
}

And the java to use this could be:

import java.sql.*;
import java.io.*;
import oracle.jdbc.driver.*;

class curvar
{
  public static void main (String args [])

                     throws SQLException, ClassNotFoundException
  {
      String driver_class = "oracle.jdbc.driver.OracleDriver";
      String connect_string = "jdbc:oracle:thin:@slackdog:1521:oracle8";

      String query = "begin :1 := sp_listEmp; end;";
      Connection conn;

      Class.forName(driver_class);
      conn = DriverManager.getConnection(connect_string, "scott", "tiger");

      CallableStatement cstmt = conn.prepareCall(query);
      cstmt.registerOutParameter(1,OracleTypes.CURSOR);
      cstmt.execute();
      ResultSet rset = (ResultSet)cstmt.getObject(1);

      while (rset.next ())
        System.out.println( rset.getString (1) );
      cstmt.close();

  }
}

The following is thanks to marktoml_at_hotmail.com (mark tomlinson)..

If you use ODBC here is a working example, but it requires the use of the 8.0.5.2.0 or later Oracle ODBC driver, and an 8.0.5 server.

'
' 1) Create a form with 1 Text control (Text1) and 1 List Control (List1) and
' 1 Button (btnExecute).
' 2) The only code that you need is a Click method on your button. Here is the Code.
'
'
Private Sub btnExecute_Click()

'PL/SQL Code
'===========
'
'CREATE OR REPLACE package reftest as
' cursor c1 is select ename from emp;
' type empCur is ref cursor return c1%ROWTYPE;
' Procedure GetEmpData(en in varchar2,EmpCursor in out empCur);
'END;
'
'
'CREATE OR REPLACE package body reftest as
'   Procedure GetEmpData
'(en in varchar2,EmpCursor in out empCur) is
'begin
' open EmpCursor for select ename from emp where ename LIKE en;
'end;
'end;
'
     Dim cn As New rdoConnection
     Dim qd As rdoQuery
     Dim rs As rdoResultset
     Dim cl As rdoColumn
     Static Number As Integer
     
     List1.Clear
     Number = 0
     cn.Connect = "uid=scott; pwd=tiger; DSN=MSLANGORL;"
     'enable the MS Cursor library
     cn.CursorDriver = rdUseOdbc
     'Make the connection
     cn.EstablishConnection rdNoDriverPrompt
      
     sSQL = "{call RefTest.GetEmpData(?,?)}"
     
     Set qd = cn.CreateQuery("", sSQL)
          
     qd.rdoParameters(0).Type = rdTypeVARCHAR
     qd(0).Direction = rdParamInputOutput
     qd(0).Value = Text1.Text
     qd.rdoParameters(1).Type = rdTypeVARCHAR

     'Dynamic or Keyset is meaningless here
     Set rs = qd.OpenResultset(rdOpenStatic)

     Do
        Debug.Print
        Debug.Print
        
        Do Until rs.EOF
            For Each cl In rs.rdoColumns
                 If IsNull(cl.Value) Then
                    List1.AddItem "(null)"
                    ' Debug.Print " "; cl.Name; "NULL"; Error trap for
null fields
                Else
                    List1.AddItem cl.Value
                    ' Debug.Print " "; cl.Name; " "; cl.Value;
                End If
            Next
            Debug.Print
            rs.MoveNext
        Loop
     Loop While rs.MoreResults
     cn.Close

End Sub

>I think you can do it with DBMS_OUTPUT.
>But I've never even bothered to try.
>
>
>Sent via Deja.com http://www.deja.com/
>Share what you know. Learn what you don't.

--
See http://govt.us.oracle.com/~tkyte/ for my columns 'Digging-in to Oracle8i'... Current article is "Part I of V, Autonomous Transactions" updated June 21'st  

Thomas Kyte                   tkyte_at_us.oracle.com
Oracle Service Industries     Reston, VA   USA

Opinions are mine and do not necessarily reflect those of Oracle Corporation Received on Tue Aug 03 1999 - 10:33:59 CDT