Question

我更新表的python代码是这样的： -

def reportMatch(winner, loser):
    """Records the outcome of a single match between two players.

    Args:
      winner:  the id number of the player who won
      loser:  the id number of the player who lost
    """
    conn=connect()
    cur=conn.cursor()
    sql="UPDATE players SET wins = wins + 1 WHERE id = winner;"
    cur.execute(sql)
    sql="UPDATE players SET losses = losses + 1 WHERE id = loser;"
    cur.execute(sql)
    sql="INSERT INTO matches (player_a,player_b,result) VALUES (%s,%s,%s);"
    data=(winner,loser,winner)
    cur.execute(sql,data)
    cur.close()
    conn.close()
    return

它正在做的是更新匹配表和玩家，如下所示： -

DROP TABLE IF EXISTS players CASCADE;
CREATE TABLE players(
    id SERIAL PRIMARY KEY,
    pl_name TEXT,
    wins INTEGER DEFAULT 0,
    losses INTEGER DEFAULT 0,
    draws INTEGER DEFAULT 0,
    matches INTEGER DEFAULT 0
        );

DROP TABLE IF EXISTS matches CASCADE;
CREATE TABLE matches(
    id SERIAL PRIMARY KEY,
    pl_a INTEGER REFERENCES players(id),
    pl_b INTEGER REFERENCES players(id),
    result INTEGER DEFAULT NULL
        );

现在，当我运行上述函数时，我得到的错误是： -

Traceback (most recent call last):
  File "tournament_test.py", line 153, in <module>
    testReportMatches()
  File "tournament_test.py", line 84, in testReportMatches
    reportMatch(id1, id2)
  File "/vagrant/tournament/tournament.py", line 99, in reportMatch
    cur.execute(sql)
psycopg2.ProgrammingError: column "winner" does not exist
LINE 1: UPDATE players SET wins = wins + 1 WHERE id = winner;
                                                      ^
HINT:  Perhaps you meant to reference the column "players.wins".

我被困在这一点上，我不知道如何比较＆＃39; id＆＃39;使用＆＃39; id＆＃39;我在变量＆＃39;获胜者＆＃39;

中收到的

我只想更新id与获胜者ID匹配的行。我是新手，对于这些蹩脚的问题感到遗憾，但我正在加快学习的步伐。请帮助，谢谢。

Answer 1

要在SQL查询中使用python变量，可以使查询的相关部分成为%s的参数：

sql = "UPDATE players SET wins = wins + 1 WHERE id = %s;"

执行它时，将参数作为元组参数传递给execute方法：

cur.execute(sql, (winner,))

Psql Hint没有任何意义

1 个答案: