Postgres异常：查询未返回任何结果。 [英] Postgres Exception : No results were returned by the query.

问题描述

我正在尝试在表格中插入一些行...我正在使用 postgressql-7.2.jar。

I am trying to insert some rows in to a table... I am using postgressql-7.2.jar.

我得到了以下异常

org.postgresql.util.PSQLException：查询未返回任何结果。

at org .postgresql.jdbc2.AbstractJdbc2Statement.executeQuery（AbstractJdbc2Statement.java:255）

org.postgresql.util.PSQLException: No results were returned by the query.
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeQuery(AbstractJdbc2Statement.java:255)

我已经使用Google搜索，可能的原因是

I have already Googled and the possible reasons suggested are

1. 使用 executeUpdate（）方法或执行（ ）方法而不是 executeQuery（）方法。

1. Use executeUpdate() method or execute() method instead of executeQuery() method.

这可能是因为罐子问题;尝试其他版本的postgres jar。

This could possibly be because of jar problem; try other versions of postgres jars.

在某些地方，他们保存它可能是因为堆空间错误。

In some places they save it could be because of heap space error.

我已经尝试了所有这三种解决方案但没有一种方法有效...

I have tried all the three solutions but none of them work...

我没有粘贴我刚刚使用 statement.executeUpdate（queryString）的代码。
插入语句将数据加载到表中但仍然出现此错误。

I am not pasting the code since I have just used statement.executeUpdate(queryString). The insert statements load the data in to the table but still I get this error.

有人可以帮我解决这个问题吗？

Can some one help me out in this?

推荐答案

这个代码适用于我运行PostgreSQL 8.1及其驱动程序。也许它可以成为查找你的错误的模板。

This code works perfectly for me running PostgreSQL 8.1 and its driver. Perhaps it can be a template for finding what's wrong with yours.

您需要一个名为PERSON的表，其中包含PERSON_ID，FIRST_NAME，LAST_NAME列。我将PERSON_ID设为自动递增的主键。

You need a single table named PERSON with columns PERSON_ID, FIRST_NAME, LAST_NAME. I made PERSON_ID the auto incremented primary key.

package persistence;

import java.sql.*;
import java.util.*;

public class DatabaseUtils
{
    private static final String DEFAULT_DRIVER = "org.postgresql.Driver";
    private static final String DEFAULT_URL = "jdbc:postgresql://localhost:5432/party";
    private static final String DEFAULT_USERNAME = "pgsuper";
    private static final String DEFAULT_PASSWORD = "pgsuper";

    public static void main(String[] args)
    {
        String driver = ((args.length > 0) ? args[0] : DEFAULT_DRIVER);
        String url = ((args.length > 1) ? args[1] : DEFAULT_URL);
        String username = ((args.length > 2) ? args[2] : DEFAULT_USERNAME);
        String password = ((args.length > 3) ? args[3] : DEFAULT_PASSWORD);

        Connection connection = null;

        try
        {
            connection = createConnection(driver, url, username, password);
            DatabaseMetaData meta = connection.getMetaData();
            System.out.println(meta.getDatabaseProductName());
            System.out.println(meta.getDatabaseProductVersion());

            String sqlQuery = "SELECT PERSON_ID, FIRST_NAME, LAST_NAME FROM PERSON ORDER BY LAST_NAME";
            System.out.println("before insert: " + query(connection, sqlQuery, Collections.EMPTY_LIST));

            connection.setAutoCommit(false);
            String sqlUpdate = "INSERT INTO PERSON(FIRST_NAME, LAST_NAME) VALUES(?,?)";
            List parameters = Arrays.asList( "Foo", "Bar" );
            int numRowsUpdated = update(connection, sqlUpdate, parameters);
            connection.commit();

            System.out.println("# rows inserted: " + numRowsUpdated);
            System.out.println("after insert: " + query(connection, sqlQuery, Collections.EMPTY_LIST));
        }
        catch (Exception e)
        {
            rollback(connection);
            e.printStackTrace();
        }
        finally
        {
            close(connection);
        }
    }

    public static Connection createConnection(String driver, String url, String username, String password) throws ClassNotFoundException, SQLException
    {
        Class.forName(driver);

        if ((username == null) || (password == null) || (username.trim().length() == 0) || (password.trim().length() == 0))
        {
            return DriverManager.getConnection(url);
        }
        else
        {
            return DriverManager.getConnection(url, username, password);
        }
    }

    public static void close(Connection connection)
    {
        try
        {
            if (connection != null)
            {
                connection.close();
            }
        }
        catch (SQLException e)
        {
            e.printStackTrace();
        }
    }


    public static void close(Statement st)
    {
        try
        {
            if (st != null)
            {
                st.close();
            }
        }
        catch (SQLException e)
        {
            e.printStackTrace();
        }
    }

    public static void close(ResultSet rs)
    {
        try
        {
            if (rs != null)
            {
                rs.close();
            }
        }
        catch (SQLException e)
        {
            e.printStackTrace();
        }
    }

    public static void rollback(Connection connection)
    {
        try
        {
            if (connection != null)
            {
                connection.rollback();
            }
        }
        catch (SQLException e)
        {
            e.printStackTrace();
        }
    }

    public static List<Map<String, Object>> map(ResultSet rs) throws SQLException
    {
        List<Map<String, Object>> results = new ArrayList<Map<String, Object>>();

        try
        {
            if (rs != null)
            {
                ResultSetMetaData meta = rs.getMetaData();
                int numColumns = meta.getColumnCount();
                while (rs.next())
                {
                    Map<String, Object> row = new HashMap<String, Object>();
                    for (int i = 1; i <= numColumns; ++i)
                    {
                        String name = meta.getColumnName(i);
                        Object value = rs.getObject(i);
                        row.put(name, value);
                    }
                    results.add(row);
                }
            }
        }
        finally
        {
            close(rs);
        }

        return results;
    }

    public static List<Map<String, Object>> query(Connection connection, String sql, List<Object> parameters) throws SQLException
    {
        List<Map<String, Object>> results = null;

        PreparedStatement ps = null;
        ResultSet rs = null;

        try
        {
            ps = connection.prepareStatement(sql);

            int i = 0;
            for (Object parameter : parameters)
            {
                ps.setObject(++i, parameter);
            }

            rs = ps.executeQuery();
            results = map(rs);
        }
        finally
        {
            close(rs);
            close(ps);
        }

        return results;
    }

    public static int update(Connection connection, String sql, List<Object> parameters) throws SQLException
    {
        int numRowsUpdated = 0;

        PreparedStatement ps = null;

        try
        {
            ps = connection.prepareStatement(sql);

            int i = 0;
            for (Object parameter : parameters)
            {
                ps.setObject(++i, parameter);
            }

            numRowsUpdated = ps.executeUpdate();
        }
        finally
        {
            close(ps);
        }

        return numRowsUpdated;
    }
}

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