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python - SQL 字符串在 SQLIte 列名中抛出带有特殊字符的错误

问题描述

我有一个 SQLite 数据库。在所述表中存在一列，其中包含“-”/减号。这个 SQLite 数据库是使用 pandas（SQLAlchemy 作为引擎）从 python 3.6 创建的。该表和该列的创建没有问题。但是，当我想在此表上构建查询时，我不知道如何转义“-”字符。这是一个简短的例子：

#imports
import numpy as np
import pandas as pd
from sqlalchemy import create_engine

#create df
df = pd.DataFrame(np.random.rand(10,2),columns=['Column1','Prob-Column'])
# create engine to connect to db
engine = create_engine('sqlite://')
#create table in db
df.to_sql('my_table',engine,if_exists='replace')

# variables
vals = '(?)'
fil = ('key',)

# create sql string
sq = 'SELECT * FROM {t} WHERE {c1} IN {vals} GROUP BY {c2}'\
.format(t='my_table',c1='Column1',c2='Prob-Column',vals = vals)

#write query to pandas df
df = pd.read_sql_query(sq,engine,params=(fil))

跟踪如下：

OperationalError: (sqlite3.OperationalError) no such column: Prob [SQL: 'SELECT * FROM my_table WHERE Column1 IN (?) GROUP BY Prob-Column'] [parameters: ('key',)] (Background on this error at: http://sqlalche.me/e/e3q8)

标签： pythonpandassqlitesqlalchemyescaping

解决方案

这是解决方案。列名只需要用双引号括起来，即在单引号的内侧，这样 c2='"Prob-Column"'。无论如何，希望这对其他人有帮助。

#imports
import numpy as np
import pandas as pd
from sqlalchemy import create_engine

#create df
df = pd.DataFrame(np.random.rand(10,2),columns=['Column1','Prob-Column'])
# create engine to connect to db
engine = create_engine('sqlite://')
#create table in db
df.to_sql('my_table',engine,if_exists='replace')

# variables
vals = '(?)'
fil = ('key',)

# create sql string
sq = 'SELECT * FROM {t} WHERE {c1} IN {vals} GROUP BY {c2}'\
.format(t='my_table',c1='Column1',c2='"Prob-Column"',vals = vals)

#write query to pandas df
df = pd.read_sql_query(sq,engine,params=(fil))

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