Question

我正在尝试编写一个小程序，它必须存储和检索数据库中的值。数据库是对象关系。

这是DDL声明：

create or replace type Guy as object (name varchar(80), address varchar(80), dateOfBirth date)

create or replace type KnownLanguages as varray(10) of varchar(80)

create table Coders (person_ Guy, description clob, knownLanguages_ KnownLanguages)

这是我的Java代码：

package adbms;

import java.sql.Clob;
import java.sql.Connection;
import java.sql.Date;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

import oracle.jdbc.OracleDriver;
import oracle.jdbc.driver.OraclePreparedStatement;
import oracle.jdbc.driver.OracleResultSet;
import oracle.sql.ARRAY;
import oracle.sql.ArrayDescriptor;

public class SimpleJdbcApplication {
    public static final String DRIVER_TYPE = "thin";
    public static final String HOST_NAME = "localhost";
    public static final int PORT = 1521;
    public static final String DATABASE_SID = "ralphdb";
    public static final String USER_NAME = "scott";
    public static final String PASSWORD = "tiger";
    public static final String URL = String.format("jdbc:oracle:%s:@%s:%d:%s", DRIVER_TYPE, HOST_NAME, PORT, DATABASE_SID);

    private static Connection connection;
    private static Scanner read;
    private static PreparedStatement insertStatement;
    private static PreparedStatement deleteStatement;
    private static PreparedStatement updateStatement;
    private static PreparedStatement displayStatement;

    static {
        try {
            System.out.println(URL);
            read = new Scanner(System.in);
            DriverManager.registerDriver(new OracleDriver());
            connection = DriverManager.getConnection(URL, USER_NAME, PASSWORD);
            insertStatement = connection.prepareStatement("insert into Coders values( Guy(?,?,?) , ? , ?)");
            deleteStatement = connection.prepareStatement("delete from Coders where person_.name=?");
            updateStatement = connection.prepareStatement("update Coders set person_.name=? where person_.name=?");
            displayStatement = connection.prepareStatement("select * from Coders");
        } catch (Exception x) {
            x.printStackTrace();
        }
    }

    public static void main(String... args) throws SQLException {
        while (true) {
            System.out.println("Enter your choice.");
            System.out.println("1. Insert");
            System.out.println("2. Delete");
            System.out.println("2. Update");
            System.out.println("4. Display");
            System.out.println("5. Enter a direct query");
            System.out.println("6. Exit");
            switch (read.nextInt()) {
                case 1:
                    insertCoder();
                    break;
                case 2:
                    removeCoder();
                    break;
                case 3:
                    updateCoder();
                    break;
                case 4:
                    displayAllCoders();
                    break;
                case 5:
                    processDirectQuerry();
                    break;
                default:
                    System.exit(0);
            }
        }
    }

    private static void processDirectQuerry() throws SQLException {
        System.out.println("Enter the query.");
        String query = read.nextLine();
        connection.createStatement().execute(query);
    }

    private static void displayAllCoders() throws SQLException {
        ResultSet resultSet = displayStatement.executeQuery();
        System.out.println("Name\tAddress\tDate of birth\tDescription\tKnown Languages");
        while (resultSet.next()) {
            System.out.print(resultSet.getString("person_.name")+"\t");
            System.out.print(resultSet.getString("person_.address")+"\t");
            System.out.print(resultSet.getDate("person_.dateOfBirth")+"\t");
            Clob description = resultSet.getClob("description");
            System.out.print(description.getSubString(1L, (int) description.length()));
            ARRAY oraArray = ((OracleResultSet) resultSet).getARRAY("knownLanguages_");
            String[] languagesArray = (String[]) oraArray.getArray();
            for (String language : languagesArray) {
                System.out.print(language + " ");
            }
            System.out.println();
        }
    }

    private static void updateCoder() throws SQLException {
        System.out.println("Enter the name of the coder whose name is to be updated.");
        String originalName = read.nextLine();
        System.out.println("ENter the new name.");
        String newName = read.nextLine();
        updateStatement.setString(1, newName);
        updateStatement.setString(2, originalName);
        updateStatement.executeUpdate();
    }

    private static void removeCoder() throws SQLException {
        System.out.println("Enter the name of coder to be removed.");
        String name = read.nextLine();
        deleteStatement.setString(1, name);
        deleteStatement.executeUpdate();
    }

    private static void insertCoder() throws SQLException {
        read = new Scanner(System.in);
        System.out.println("Enter the name, address and date of birth.");
        String name = read.nextLine();
        String address = read.nextLine();
        String dateOfBirth = read.nextLine();
        System.out.println("Enter a brief description.");
        String description = read.nextLine();
        List<String> languagesList = new ArrayList<String>();
        System.out.println("Enter names of known languages. (At most 10.) Type 'done' when you're done.");
        String token = null;
        int i = 0;
        while (i < 10 && !(token = read.nextLine()).equalsIgnoreCase("done")) {
            languagesList.add(token);
                    i++;
        }
        insertStatement.setString(1, name);
        insertStatement.setString(2, address);
        insertStatement.setDate(3, Date.valueOf(dateOfBirth));
        insertStatement.setString(4, description);
        //String[] languagesArray = (String[]) languagesList.toArray();
        Object[] languagesArray = languagesList.toArray();
        ArrayDescriptor arrayDescriptor = ArrayDescriptor.createDescriptor("KnownLanguages", connection);
        ARRAY oraArray = new ARRAY(arrayDescriptor, connection, languagesArray);
        ((OraclePreparedStatement) insertStatement).setARRAY(5, oraArray);
        insertStatement.executeUpdate();
    }
}

代码编译得很好。但是当我尝试在数据库中插入值时，它会出现以下错误

F：\ adb＆gt; java SimpleJdbcApplication JDBC：神谕：薄：@ 127.0.0.1：1521：ralphdb 输入您的选择。 1.插入 2.删除 2.更新 4.显示 5.输入直接查询 6.退出1输入姓名，地址和出生日期。拉胡尔孟买1989-12-22 输入简要说明。快乐回车已知语言的名称。（最多 10.）完成后输入'done'。 c ++ c java done线程“main”中的异常 java.sql.SQLException：名称无效模式：SYSTEM.K nownLanguages at oracle.jdbc.driver.DatabaseError.throwSqlException（DatabaseError.java ：112） at oracle.jdbc.driver.DatabaseError.throwSqlException（DatabaseError.java ：146）在oracle.jdbc.oracore.OracleTypeADT.initMetadata（OracleTypeADT.java:463）） at oracle.jdbc.oracore.OracleTypeADT.init（OracleTypeADT.java:362） at oracle.sql.ArrayDescriptor.initPickler（ArrayDescriptor.java:1756）在oracle.sql.ArrayDescriptor。（ArrayDescriptor.java:272） at oracle.sql.ArrayDescriptor.createDescriptor（ArrayDescriptor.java:196） at oracle.sql.ArrayDescriptor.createDescriptor（ArrayDescriptor.java:165） at oracle.sql.ArrayDescriptor.createDescriptor（ArrayDescriptor.java:150） at oracle.sql.ArrayDescriptor.createDescriptor（ArrayDescriptor.java:115）在SimpleJdbcApplication.insertCoder（SimpleJdbcApplication.java:143）在SimpleJdbcApplication.main（SimpleJdbcApplication.java:62） F：\ ADB＆GT;

我认为我处理VARRAY的方式有问题。请帮帮我......

谢谢！： - ）

Answer 1

似乎是这一行引发了异常：

ArrayDescriptor arrayDescriptor = ArrayDescriptor.createDescriptor("KnownLanguages", connection);

我认为问题在于它没有解析数据库中的类型名称。我相信我在过去发现类型查找区分大小写，默认情况下在Oracle中类型名称都是大写的。因此，请尝试使用上面一行中的“KNOWNLANGUAGES”。

此外，它似乎在查看SYSTEM架构，虽然我不知道为什么。如果类型不属于SYSTEM，则可能还需要在描述符调用中明确指定（例如“SCOTT.KNOWNLANGUAGES”）。

如何在JDBC中处理VARRAY（Oracle 9i）？

1 个答案: