Oracle SQL - 如何使用 JSP 调用 ODCI 流水线函数

Posted 2023-03-23

【中文标题】Oracle SQL - 如何使用 JSP 调用 ODCI 流水线函数

【英文标题】：Oracle SQL - How can I call the ODCI pipelined function using JSP

【发布时间】：2018-11-05 09:00:44

【问题描述】：

以下是来自的确切实现 https://docs.oracle.com/cd/B28359_01/appdev.111/b28425/pipelined_example.htm#CHDHDHEE

假设我们有以下表格定义：

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

那么，我们得到了以下类型（一个基本类型作为对象，一个类型作为它的表）：

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

CREATE TYPE TickerTypeSet AS TABLE OF TickerType;

此外，我们还定义了一个 ODCI 类型，它在数据库中的 SQL 和 Java 存储过程中实现：

SQL：

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 存储过程：

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;
  

 

毕竟，为了有一个流水线函数可以用来创建上述表类型的表，我们需要一个 ref cursor 和 流水线函数本身。我已将 ref 光标放入一个包中。

-- 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;
/

我的问题是如何调用 StockPivot 函数以执行 JSP 并显示上述类型的表格。

我希望从模拟表格的简单选择中获得结果：

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

我曾尝试像这样调用该函数，但由于明显原因（我们需要一个引用光标作为参数）它不起作用：

SELECT * FROM TABLE(StockPivot());

提前谢谢你。

【参考方案1】：

选项 1 创建函数以返回强引用光标。

    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()));    

选项 2。您可以尝试光标表达式，它也应该可以工作。 Cursor expression.

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

【讨论】：

谢谢，这就是我要找的。​​span>