无法通过Python/psycopg2将数据插入Postgresql数据库

Question

使用一个方法（见下图），我构建了一个insert命令，将一个条目（存储为字典）插入到我的postgresql数据库中。不过，当我把命令传给当前执行我得到一个语法错误。我真的不知道为什么会发生这个错误。在

>>> print insert_string
"""INSERT INTO db_test (album, dj, datetime_scraped, artist, playdatetime, label, showblock, playid, showtitle, time, station, source_url, showgenre, songtitle, source_title) VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s);""", (item['album'], item['dj'], item['datetime_scraped'], item['artist'], item['playdatetime'], item['label'], item['showblock'], item['playid'], item['showtitle'], item['time'], item['station'], item['source_url'], item['showgenre'], item['songtitle'], item['source_title'])

>>> cur.execute(insert_string)

psycopg2.ProgrammingError: syntax error at or near """"INSERT INTO db_test (album, dj, datetime_scraped, artist, playdatetime, label, showblock, playid, showtitle, time, station, source_url, showgenre, songtitle, source_title) VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s);""""
    LINE 1: """INSERT INTO db_test (album, dj, datetime_scraped, artis...

下面是这个insert命令的一个更“友好”的版本：

^{pr2}$

用于生成插入的方法：

def build_insert(self, table_name, item):
    if len(item) == 0:
      log.msg("Build_insert failed.  Delivered item was empty.", level=log.ERROR)
      return ''

    #itemKeys = item.keys()
    itemValues = []
    for key in item.keys(): # Iterate through each key, surrounded by item[' '], seperated by comma
      itemValues.append('item[\'{theKey}\']'.format(theKey=key))

    sqlCommand = "\"\"\"INSERT INTO {table} ({keys}) VALUES ({value_symbols});\"\"\", ({values})".format(
      table = table_name, #table to insert into, provided as method's argument
      keys = ", ".join(item.keys()), #iterate through keys, seperated by comma
      value_symbols = ", ".join("%s" for key in itemValues), #create a %s for each key
      values = ", ".join(itemValues))

    return sqlCommand

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

编辑：

我使用了Gringo Suaves的建议，除了对build_insert方法做了一些小的更改（根据存在的键的数量，根据需要创建尽可能多的%s符号）。在

def build_insert(self, table_name, item):
  if len(item) == 0:
    log.msg("Build_insert failed.  Delivered item was empty.", level=log.ERROR)
    return ''

  keys = item.keys()
  values = [ item[k] for k in keys] # make a list of each key

  sqlCommand = 'INSERT INTO {table} ({keys}) VALUES ({value_symbols});'.format(
    table = table_name, #table to insert into, provided as method's argument
    keys = ", ".join(keys), #iterate through keys, seperated by comma
    value_symbols = ", ".join("%s" for value in values) #create a %s for each key
    )
  return (sqlCommand, values)

Answer 1

字符串不是有效的SQL语句，它包含大量python cruft。在

我想我已经修好了方法：

def build_insert(self, table_name, item):
    if len(item) == 0:
      log.msg('Build_insert failed.  Delivered item was empty.', level=log.ERROR)
      return ''

    keys = item.keys()
    values = [ item[k] for k in keys ]

    sqlCommand = 'INSERT INTO {table} ({keys}) VALUES ({placeholders});'.format(
      table = table_name,
      keys = ', '.join(keys),
      placeholders = ', '.join([ "'%s'" for v in values ])  # extra quotes may not be necessary
    )

    return (sqlCommand, values)

对于一些伪数据，它返回以下元组。为了清楚起见，我添加了一些新行：

^{pr2}$

最后，把它传给当前执行（）：

instr, data = build_insert(self, 'thetable', item)
cur.execute(instr, data)

Answer 2

缺少“%”（在为查询传递参数之前）。在

基本上，您必须确保“%s”被实际值替换。在

例如： msg='世界' Test='你好%s'%msg

“%”将用变量msg中存储的内容替换占位符。在

您可以在error msg中看到psycopg正在获取带有实际“%s”的查询字符串，这就是它无法运行的原因。在