Java Postgres 异常：查询未返回任何结果。

Postgres Exception : No results were returned by the query.

提问by Balaji.N.S

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

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

I get the following exception

我收到以下异常

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

org.postgresql.util.PSQLException：查询未返回任何结果。
在 org.postgresql.jdbc2.AbstractJdbc2Statement.executeQuery(AbstractJdbc2Statement.java:255)

I have already Googled and the possible reasons suggested are

我已经用谷歌搜索过，建议的可能原因是

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

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

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

1. 使用executeUpdate()方法或execute()方法代替executeQuery()方法。

2. 这可能是因为 jar 问题；尝试其他版本的 postgres jar。

3. 在某些地方他们保存它可能是因为堆空间错误。

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

我已经尝试了所有三种解决方案，但它们都不起作用......

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

我没有粘贴代码，因为我刚刚使用了statement.executeUpdate(queryString). 在INSERT语句加载数据到表中，但我仍然得到这个错误。

Can some one help me out in this?

有人可以帮我解决这个问题吗？

采纳答案by duffymo

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.

这段代码非常适合我运行 PostgreSQL 8.1 及其驱动程序。也许它可以作为一个模板来找出你的问题所在。

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

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。

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;
    }
}

回答by matt b

What type of SQL statement are you trying to run with executeQuery()? It should not be an INSERT or UPDATE - these are not queries.

你想用什么类型的 SQL 语句运行executeQuery()？它不应该是 INSERT 或 UPDATE - 这些不是查询。

Without posting the actual SQL statement, code samples, or what the table looks like - it's pretty hard to actually help you with your problem. Without specifics all we can do is guess.

不发布实际的 SQL 语句、代码示例或表的外观 - 很难真正帮助您解决问题。没有细节，我们所能做的就是猜测。

回答by Thorbj?rn Ravn Andersen

A statement inserting rows does not return any rows back as a result, as opposed to a SELECT.

与 SELECT 相反，插入行的语句不会返回任何行作为结果。