pandas to_sql pandas方法改变sqlite表的scheme
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to_sql pandas method changes the scheme of sqlite tables
提问by drastega
When I write Pandas DataFrame to my SQLite database using to_sqlmethod it changes the .schemaof my table even if I use if_exists='append'. For example after execution
当我使用to_sql方法将 Pandas DataFrame 写入我的 SQLite 数据库时.schema，即使我使用if_exists='append'. 例如执行后
with sqlite3.connect('my_db.sqlite') as cnx:
df.to_sql('Resolved', cnx, if_exists='append')
original .schema:
原文.schema：
CREATE TABLE `Resolved` (
`Name` TEXT NOT NULL COLLATE NOCASE,
`Count` INTEGER NOT NULL,
`Obs_Date` TEXT NOT NULL,
`Bessel_year` REAL NOT NULL,
`Filter` TEXT NOT NULL,
`Comments` TEXT COLLATE NOCASE
);
changes to:
更改为：
CREATE TABLE Resolved (
[Name] TEXT,
[Count] INTEGER,
[Obs_Date] TEXT,
[Bessel_year] REAL,
[Filter] TEXT,
[Comments] TEXT
);
How to save the original scheme of my table? I use pandas 0.14.0, Python 2.7.5
如何保存我的表的原始方案？我使用Pandas 0.14.0，Python 2.7.5
回答by joris
Starting from 0.14 (what you are using), the sql functions are refactored to use sqlalchemyto improve the functionality`. See the whatsnewand docson this.
The raw sqlite3 connection is still supported as a fallback (but that is the only sql flavor that is supported without sqlalchemy).
从 0.14（您正在使用的）开始，sql 函数被重构以用于sqlalchemy改进功能` 。见whatsnew和文档这一点。
仍然支持原始 sqlite3 连接作为后备（但这是唯一不支持 sqlalchemy 的 sql 风格）。
Using sqlalchemy should solve the issue. For this you can just create a sqlalchemy engine instead of the direct sqlite connection cnx:
使用 sqlalchemy 应该可以解决这个问题。为此，您可以创建一个 sqlalchemy 引擎而不是直接的 sqlite 连接cnx：
engine = sqlalchemy.create_engine('sqlite:///my_db.sqlite')
df.to_sql('Resolved', engine, if_exists='append')
But I filed an issue for the case with the sqlite cnx fallback option: https://github.com/pydata/pandas/issues/7355
但是我使用 sqlite cnx 回退选项为该案例提交了一个问题：https: //github.com/pydata/pandas/issues/7355
