Oracle SQL - 如何使用 JSP 調用 ODCI 流水線函數

Question

以下是來自https://docs.oracle.com/cd/B28359_01/appdev.111/b28425/pipelined_example.htm#CHDHDHEE的確切實現

假設我們有以下表格定義：

CREATE TABLE StockTable (
  ticker VARCHAR(4),
  openprice NUMBER,
  closeprice NUMBER
);

然后，我們有以下類型（一個基本類型作為對象，一個類型作為它的表）：

CREATE TYPE TickerType AS OBJECT
(
  ticker VARCHAR2(4),
  PriceType VARCHAR2(1),
   price NUMBER
);
/

CREATE TYPE TickerTypeSet AS TABLE OF TickerType;

此外，我們還定義了一個 ODCI 類型，並在數據庫中的 SQL 和 Java 存儲過程中實現了它：

查詢語句：

CREATE OR REPLACE TYPE StockPivotImpl AS OBJECT
(
  key INTEGER,

  STATIC FUNCTION ODCITableStart(sctx OUT StockPivotImpl, cur SYS_REFCURSOR)
    RETURN NUMBER
    AS LANGUAGE JAVA
    NAME 'StockPivotImpl.ODCITableStart(oracle.sql.STRUCT[], java.sql.ResultSet) return java.math.BigDecimal',

  MEMBER FUNCTION ODCITableFetch(self IN OUT StockPivotImpl, nrows IN NUMBER,
                                 outSet OUT TickerTypeSet) RETURN NUMBER
    AS LANGUAGE JAVA
    NAME 'StockPivotImpl.ODCITableFetch(java.math.BigDecimal, oracle.sql.ARRAY[]) return java.math.BigDecimal',

  MEMBER FUNCTION ODCITableClose(self IN StockPivotImpl) RETURN NUMBER
    AS LANGUAGE JAVA
    NAME 'StockPivotImpl.ODCITableClose() return java.math.BigDecimal'

);
/

Java存儲過程：

import java.io.*;
import java.util.*;
import oracle.sql.*;
import java.sql.*;
import java.math.BigDecimal;
import oracle.CartridgeServices.*;

// stored context type

public class StoredCtx
{
  ResultSet rset;
  public StoredCtx(ResultSet rs) { rset=rs; }
}

// implementation type

public class StockPivotImpl implements SQLData 
{
  private BigDecimal key;

  final static BigDecimal SUCCESS = new BigDecimal(0);
  final static BigDecimal ERROR = new BigDecimal(1);

  // Implement SQLData interface.

  String sql_type;
  public String getSQLTypeName() throws SQLException 
  {
    return sql_type;
  }

  public void readSQL(SQLInput stream, String typeName) throws SQLException 
  {
    sql_type = typeName;
    key = stream.readBigDecimal();
  }

  public void writeSQL(SQLOutput stream) throws SQLException 
  {
    stream.writeBigDecimal(key);
  }

  // type methods implementing ODCITable interface

  static public BigDecimal ODCITableStart(STRUCT[] sctx,ResultSet rset)
    throws SQLException 
  {
    Connection conn = DriverManager.getConnection("jdbc:default:connection:");

    // create a stored context and store the result set in it
    StoredCtx ctx=new StoredCtx(rset);

    // register stored context with cartridge services
    int key;
    try {
      key = ContextManager.setContext(ctx);
    } catch (CountException ce) {
      return ERROR;
    }

    // create a StockPivotImpl instance and store the key in it
    Object[] impAttr = new Object[1];
    impAttr[0] = new BigDecimal(key); 
    StructDescriptor sd = new StructDescriptor("STOCKPIVOTIMPL",conn);
    sctx[0] = new STRUCT(sd,conn,impAttr);

    return SUCCESS;
  }

  public BigDecimal ODCITableFetch(BigDecimal nrows, ARRAY[] outSet)
    throws SQLException 
  {
    Connection conn = DriverManager.getConnection("jdbc:default:connection:");

    // retrieve stored context using the key
    StoredCtx ctx;
    try {
      ctx=(StoredCtx)ContextManager.getContext(key.intValue());
    } catch (InvalidKeyException ik ) {
      return ERROR;
    }

    // get the nrows parameter, but return up to 10 rows
    int nrowsval = nrows.intValue();
    if (nrowsval>10) nrowsval=10;

    // create a vector for the fetched rows
    Vector v = new Vector(nrowsval);
    int i=0;

    StructDescriptor outDesc = 
      StructDescriptor.createDescriptor("TICKERTYPE", conn);
    Object[] out_attr = new Object[3];

    while(nrowsval>0 && ctx.rset.next()){
      out_attr[0] = (Object)ctx.rset.getString(1);
      out_attr[1] = (Object)new String("O");
      out_attr[2] = (Object)new BigDecimal(ctx.rset.getFloat(2));
      v.add((Object)new STRUCT(outDesc, conn, out_attr));

      out_attr[1] = (Object)new String("C");
      out_attr[2] = (Object)new BigDecimal(ctx.rset.getFloat(3));
      v.add((Object)new STRUCT(outDesc, conn, out_attr));

      i+=2;
      nrowsval-=2;
    }

    // return if no rows found
    if(i==0) return SUCCESS;

    // create the output ARRAY using the vector
    Object out_arr[] = v.toArray();
    ArrayDescriptor ad = new ArrayDescriptor("TICKERTYPESET",conn);
    outSet[0] = new ARRAY(ad,conn,out_arr);

    return SUCCESS;
  }

  public BigDecimal ODCITableClose() throws SQLException {

    // retrieve stored context using the key, and remove from ContextManager
    StoredCtx ctx;
    try {
      ctx=(StoredCtx)ContextManager.clearContext(key.intValue());
    } catch (InvalidKeyException ik ) {
      return ERROR;
    }

    // close the result set
    Statement stmt = ctx.rset.getStatement();
    ctx.rset.close();
    if(stmt!=null) stmt.close();

    return SUCCESS;
  }

} 

畢竟，為了有一個可用於創建上述表類型的表的流水線函數，我們需要有一個引用游標和流水線函數本身。 我已將 ref 光標放入一個包中。

-- Define the ref cursor type
  CREATE OR REPLACE PACKAGE refcur_pkg IS
    TYPE refcur_t IS REF CURSOR RETURN StockTable%ROWTYPE;
  END refcur_pkg;
/

  -- Create table function
  CREATE OR REPLACE FUNCTION StockPivot(p refcur_pkg.refcur_t) RETURN TickerTypeSet
  PIPELINED USING StockPivotImpl;
/

我的問題是如何調用 StockPivot 函數來執行 JSP 並顯示上述類型的表。

我期待從一個模擬表的簡單選擇中得到結果：

-----------------------------
|  column1 |  column2 | ... |
|---------------------------|
| row_data1| row_data2| ... |
| --------------------------|
|___________________________|

我試圖像這樣調用函數，但由於明顯的原因它不起作用（我們需要一個引用游標作為參數）：

SELECT * FROM TABLE(StockPivot());

先感謝您。

Answer 1

選項 1 創建函數以返回強引用游標。

    create or replace function getCursor return refcur_pkg.refcur_t  is
             c_tmp refcur_pkg.refcur_t;
            begin 
             open c_tmp for select * from StockTable;
             return c_tmp;
            end;  

SELECT * FROM TABLE(StockPivot(getCursor()));    

選項 2. 您可以嘗試使用游標表達式，它也應該可以工作。 光標表達式。

SELECT * FROM TABLE(StockPivot(Cursor(select * from StockTable)));