编程生活

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;
/
create or replace procedure getemps( p_cursor in out types.cursorType )

as

begin

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

end;

/

examples for SQLPlus, Pro*C, Java/JDBC, ODBC, ADO/ASP, DBI Perl and OCI follow:

REM SQL*Plus commands to use a cursor variable

variable c refcursor
exec :c := sp_ListEmp
print c

exec getEmps( :c )

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();
  }
}