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Tips--Using Ref Cursors To Return Recordsets

原创 Linux操作系统 作者:vongates 时间:2019-07-17 07:36:01 0 删除 编辑

Using Ref Cursors To Return Recordsets

Since Oracle 7.3 REF CURSORS have been available which allow recordsets to be returned from stored procedures, functions and packages. The example below uses a ref cursor to return a subset of the records in the EMP table.




First, a package definition is needed to hold the ref cursor type:

CREATE OR REPLACE PACKAGE Types AS 
  TYPE cursor_type IS REF CURSOR;
END Types; 
/

Note. In Oracle9i the SYS_REFCURSOR type has been added making this first step unnecessary. If you are using Oracle9i or later simply ignore this first package and replace any references to Types.cursor_type with SYS_REFCURSOR.

Next a procedure is defined to use the ref cursor:

CREATE OR REPLACE
PROCEDURE GetEmpRS (p_deptno    IN  emp.deptno%TYPE,
                    p_recordset OUT Types.cursor_type) AS 
BEGIN 
  OPEN p_recordset FOR
    SELECT ename,
           empno,
           deptno
    FROM   emp
    WHERE  deptno = p_deptno
    ORDER BY ename;
END GetEmpRS;
/

The resulting cursor can be referenced from PL/SQL as follows:

SET SERVEROUTPUT ON 1000000
DECLARE
  v_cursor  Types.cursor_type;
  v_ename   emp.ename%TYPE;
  v_empno   emp.empno%TYPE;
  v_deptno  emp.deptno%TYPE;
BEGIN
  GetEmpRS (p_deptno    => 30,
            p_recordset => v_cursor);
            
  LOOP 
    FETCH v_cursor
    INTO  v_ename, v_empno, v_deptno;
    EXIT WHEN v_cursor%NOTFOUND;
    DBMS_OUTPUT.PUT_LINE(v_ename || ' | ' || v_empno || ' | ' || v_deptno);
  END LOOP;
  CLOSE v_cursor;
END;
/

In addition the cursor can be used as an ADO Recordset:

Dim conn, cmd, rs

Set conn = Server.CreateObject("adodb.connection")
conn.Open "DSN=TSH1;UID=scott;PWD=tiger"

Set cmd = Server.CreateObject ("ADODB.Command")
Set cmd.ActiveConnection = conn
cmd.CommandText = "GetEmpRS"
cmd.CommandType = 4 'adCmdStoredProc

Dim param1
Set param1 = cmd.CreateParameter ("deptno", adInteger, adParamInput)
cmd.Parameters.Append param1
param1.Value = 30

Set rs = cmd.Execute

Do Until rs.BOF Or rs.EOF
  -- Do something
  rs.MoveNext
Loop

rs.Close
conn.Close
Set rs     = nothing
Set param1 = nothing
Set cmd    = nothing
Set conn   = nothing

The cursor can also be referenced as a Java ResultSet:

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

public class TestResultSet  {
  public TestResultSet() {
    try {
      DriverManager.registerDriver (new oracle.jdbc.OracleDriver());
      Connection conn = DriverManager.getConnection("jdbc:oracle:oci:@w2k1", "scott", "tiger");
      CallableStatement stmt = conn.prepareCall("BEGIN GetEmpRS(?, ?); END;");
      stmt.setInt(1, 30); // DEPTNO
      stmt.registerOutParameter(2, OracleTypes.CURSOR); //REF CURSOR
      stmt.execute();
      ResultSet rs = ((OracleCallableStatement)stmt).getCursor(2);
      while (rs.next()) {
        System.out.println(rs.getString("ename") + ":" + rs.getString("empno") + ":" + rs.getString("deptno")); 
      }
      rs.close();
      rs = null;
      stmt.close();
      stmt = null;
      conn.close();
      conn = null;
    }
    catch (SQLException e) {
      System.out.println(e.getLocalizedMessage());
    }
  }

  public static void main (String[] args) {
    new TestResultSet();
  }
}

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