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[英]Trouble connecting to Postgresql DB through Python's psycopg2
[英]Trouble inserting data into Postgresql db via Python/psycopg2
使用一种方法(见下),我构建一个插入命令,将一个项目(存储为字典)插入到我的postgresql数据库中。 虽然,当我将该命令传递给cur.execute时,我收到语法错误。 我真的不知道为什么会出现这个错误。
>>> 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...
这是一个更加“眼球友好”的插入命令版本:
"""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'])
用于构建插入的方法:
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,但对build_insert方法进行了一些小改动(根据所存在的键数创建尽可能多的%s符号。
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)
你的字符串不是有效的SQL语句,它包含许多python cruft。
我想我已经修复了这个方法:
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)
对于一些虚拟数据,它返回了以下元组。 为清晰起见,我添加了一些换行符:
( "INSERT INTO thetable (album, dj, datetime_scraped, artist,
playdatetime, label, showblock, playid, songtitle, time, station,
source_url, showgenre, showtitle, source_title) VALUES ('%s', '%s',
'%s', '%s', '%s', '%s', '%s', '%s', '%s', '%s', '%s', '%s', '%s',
'%s', '%s');",
['album_val', 'dj_val', 'datetime_scraped_val', 'artist_val',
'playdatetime_val', 'label_val', 'showblock_val', 'playid_val',
'songtitle_val', 'time_val', 'station_val', 'source_url_val',
'showgenre_val', 'showtitle_val', 'source_title_val']
)
最后,将它传递给cur.execute():
instr, data = build_insert(self, 'thetable', item)
cur.execute(instr, data)
您缺少'%'(在传递查询参数之前)。
基本上你必须确保'%s'被实际值替换。
例如:msg ='world'Test ='hello%s'%msg
'%'将用存储在变量msg中的任何内容替换占位符。
您可以在错误消息中看到psycopg正在获取具有实际'%s'的查询字符串,这就是为什么它不会运行的原因。
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