这是用户错误。我以错误的方式连接到无业游民和锦标赛数据库。

错误：

在无业游民中，我以无业游民身份进入psql并导入了文件。

  \i Tournament.sql 
 

然后我连接到数据库。

  \c比赛
 

然后我要退出psql来运行文件并

我需要再做一步。

修复：

p>

连接并登录数据库锦标赛后，我需要再次导入Tournament.sql文件。

日实际数据库中的关系，而不仅仅是流浪汉或以前在任何地方创建的关系。

因此在命令Vagrant ssh
之后是从Vagrant获得的＃b $ b cd / vagrant / tournament /

  psql 

 \i锦标赛.sql 

 \c锦标赛

 \i锦标赛

＃最后一次检查以确认您的关系已建立
 \dt 
 \d（表或视图）
 

这就是我所做的。该项目的其余部分很容易。我希望这可以帮助任何人在此处搜索答案，并且仅找到更多未回答但遭到批评的问题。感谢所有看到我的初学者问题并给我否定观点或停止批评我的问题形式的专家。我仍在学习，如果你们中的任何一个确实帮助我了解或解决了这个问题，那么我将无法在3天的时间内独自完成所有工作。

Intro: I have been working on building a Python backed PostgreSQL database of a Swiss style tournament using Vagrant running a Ubuntu VM for my Relational Database course in Udacity.

Question: Why does it say the table does not exist when I attempt to delete the information within the existing table?

I did a generic search to research

psycopg2.ProgrammingError

, but the information is mostly specific to other circumstances, and I was unable to make logical connections that would allow me fix this problem. I also found another Stack Overflow thread that is close to the same issue other thread here, however that issue was also never resolved. So I have created this question attempting to find someone capable of understanding my conundrum and provide some kind of hint or clue to get me working in the right direction.

I have imported the tournament database SQL file into the Vagrant VM. This deleted the two tables (players and matches) and the database (tournament) and then recreates this database and these tables. So I know the table (matches) exists. However, this is what I am getting...

Vagrant: (current vagrant error)

vagrant@vagrant:/vagrant/tournament$ python tournament_test.py
Traceback (most recent call last):
  File "tournament_test.py", line 151, in <module>
    testCount()
  File "tournament_test.py", line 17, in testCount
    deleteMatches()
  File "/vagrant/tournament/tournament.py", line 18, in deleteMatches
    cursor.execute("DELETE FROM matches;")
psycopg2.ProgrammingError: relation "matches" does not exist
LINE 1: DELETE FROM matches;
                    ^

SQL: (All from tournament.sql)

-- Table definitions for the tournament project.
--
-- Put your SQL 'create table' statements in this file; also 'create view'
-- statements if you choose to use it.
--
-- You can write comments in this file by starting them with two dashes, 
like
-- these lines here.
DROP TABLE matches;
DROP TABLE players;
DROP DATABASE tournament;
CREATE DATABASE tournament;


CREATE TABLE players (player_id SERIAL UNIQUE PRIMARY KEY, name 
VARCHAR(40));
CREATE TABLE matches (match_id SERIAL UNIQUE PRIMARY KEY,
                      winner INTEGER REFERENCES players(player_id),
                      loser INTEGER REFERENCES players (player_id));

Python: (Minimal from tournament.py)

#!/usr/bin/env python
#
# tournament.py -- implementation of a Swiss-system tournament
#

import psycopg2


def connect():
    """Connect to the PostgreSQL database.  Returns a database 
connection."""
    return psycopg2.connect("dbname=tournament")


def deleteMatches():
    """Remove all the match records from the database."""
    db = connect()
    cursor = db.cursor()
    cursor.execute("TRUNCATE matches CASCADE;")
    db.commit()
    db.close()

Python: (minimal from tournament_test.py) this is the file that verifies the tournament.py functions are working with the tournament.sql database.

#!/usr/bin/env python
#
# Test cases for tournament.py

from tournament import *

def testCount():
    """
    Test for initial player count,
             player count after 1 and 2 players registered,
             player count after players deleted.
    """
    deleteMatches()
    deletePlayers()
    c = countPlayers()
    if c == '0':
        raise TypeError(
            "countPlayers should return numeric zero, not string '0'.")
    if c != 0:
        raise ValueError("After deletion, countPlayers should return zero.")
    print "1. countPlayers() returns 0 after initial deletePlayers() 
execution."
    registerPlayer("Chandra Nalaar")
    c = countPlayers()
    if c != 1:
        raise ValueError(
            "After one player registers, countPlayers() should be 1. Got 
{c}".format(c=c))
    print "2. countPlayers() returns 1 after one player is registered."
    registerPlayer("Jace Beleren")
    c = countPlayers()
    if c != 2:
        raise ValueError(
            "After two players register, countPlayers() should be 2. Got 
{c}".format(c=c))
    print "3. countPlayers() returns 2 after two players are registered."
    deletePlayers()
    c = countPlayers()
    if c != 0:
        raise ValueError(
            "After deletion, countPlayers should return zero.")
    print "4. countPlayers() returns zero after registered players are 
deleted.\n5. Player records successfully deleted."

testCount()

Vagrant (Confirming that the table 'matches' exists within the database):

vagrant=> \dt
         List of relations
 Schema |  Name   | Type  |  Owner
--------+---------+-------+---------
 public | matches | table | vagrant
 public | players | table | vagrant
(2 rows)

Update2: Clarification to comment

I connect to the db at the beginning of my python file.

def connect()
    """Connect to the PostgreSQL database.  Returns a database 
    connection."""
    return psycopg2.connect("dbname=tournament")

This was user error. I was connecting to vagrant and the tournament database in the wrong way.

After logging into vagrant I was in the right folder accessing the right database but in the wrong method.

Error:

Once in vagrant I went to psql as user vagrant and imported the file.

\i tournament.sql

Then I connected to the database.

\c tournament

Then I was exiting psql to run the file and getting the relation does not exist error.

I needed to do one more step.

FIX:

Once connected and logged into the database tournament. I needed to import the tournament.sql file again.

That created the relations within the actual database and not just vagrant or wherever I was creating them before.

so from Vagrant after the command Vagrant ssh # run these commands separately cd /vagrant/tournament/

psql

\i tournament.sql

\c tournament

\i tournament

#last check to verify your relations were created
\dt
\d (table or view)

That is what did it for me. The rest of the project was easy. I hope this helps anyone searching for the answer on here and only finding more unanswered but heavily criticized questions. Thanks to all the experts who saw my beginner question and either gave me negative points or stopped to criticize the format of my question. I am still learning and if any of you had actually helped me understand or solve this I wouldn't have been able to do it all by myself over the course of 3 days.