Question

我正在尝试从一个csv文件创建一个sqlite数据库。经过一些搜索后，似乎可以使用pandas df。我尝试按照一些教程和文档进行操作，但无法弄清楚该错误。这是我的代码：

# Import libraries
import pandas, csv, sqlite3

# Create sqlite database and cursor
conn = sqlite3.connect('test.db')
c = conn.cursor()
# Create the table of pitches
c.execute("""CREATE TABLE IF NOT EXISTS pitches (
            pitch_type text,
            game_date text,
            release_speed real
            )""")

conn.commit()

df = pandas.read_csv('test2.csv')
df.to_sql('pitches', conn, if_exists='append', index=False)

conn.close()

运行此代码时，出现以下错误：

sqlite3.OperationalError: table pitches has no column named SL

SL是csv文件第一行中的第一个值。我不知道为什么将csv值视为列名，除非它认为csv的第一行应该是标题，并试图将其与表中的列名匹配？我也不认为是这样，因为我尝试将第一个值更改为实际的列名并遇到相同的错误。

编辑：

当我在csv中有标题时，数据框如下所示：

     pitch_type  game_date  release_speed
0            SL  8/31/2017           81.9
1            SL  8/31/2017           84.1
2            SL  8/31/2017           81.9
...         ...        ...            ...
2919         SL   8/1/2017           82.3
2920         CU   8/1/2017           78.7

[2921 rows x 3 columns]

，我收到以下错误消息：

sqlite3.OperationalError: table pitches has no column named game_date

当我将标题从csv文件中取出时

      SL  8/31/2017  81.9
0     SL  8/31/2017  84.1
1     SL  8/31/2017  81.9
2     SL  8/31/2017  84.1
...   ..        ...   ...
2918  SL   8/1/2017  82.3
2919  CU   8/1/2017  78.7

[2920 rows x 3 columns]

，我收到以下错误消息：

sqlite3.OperationalError: table pitches has no column named SL

编辑＃2：

我尝试按照this answer，使用以下代码完全从代码中删除表创建：

# Import libraries
import pandas, csv, sqlite3

# Create sqlite database and cursor
conn = sqlite3.connect('test.db')
c = conn.cursor()

df = pandas.read_csv('test2.csv')
df.to_sql('pitches', conn, if_exists='append', index=False)

conn.close()

并仍然获得

sqlite3.OperationalError: table pitches has no column named SL

错误

编辑＃3：

我将表创建代码更改为以下代码：

# Create the table of pitches
dropTable = 'DROP TABLE pitches'
c.execute(dropTable)
createTable = "CREATE TABLE IF NOT EXISTS pitches(pitch_type text, game_date text, release_speed real)"
c.execute(createTable)

，现在可以使用。不确定到底发生了什么变化，因为在我看来，它基本上是相同的，但是它可以工作。

Answer 1

如果您尝试从csv文件创建表，则可以运行sqlite3并执行以下操作：

sqlite> .mode csv
sqlite> .import c:/path/to/file/myfile.csv myTableName

Answer 2

检查您的列名。我能够成功复制您的代码而不会出错。 names变量从sqlite表中获取所有列名，您可以将它们与带有df.columns的数据帧标题进行比较。

# Import libraries
import pandas as pd, csv, sqlite3

# Create sqlite database and cursor
conn = sqlite3.connect('test.db')
c = conn.cursor()
# Create the table of pitches
c.execute("""CREATE TABLE IF NOT EXISTS pitches (
            pitch_type text,
            game_date text,
            release_speed real
            )""")
conn.commit()

test = conn.execute('SELECT * from pitches')
names = [description[0] for description in test.description]
print(names)

df = pd.DataFrame([['SL','8/31/2017','81.9']],columns = ['pitch_type','game_date','release_speed'])
df.to_sql('pitches', conn, if_exists='append', index=False)

conn.execute('SELECT * from pitches').fetchall()
>> [('SL', '8/31/2017', 81.9), ('SL', '8/31/2017', 81.9)]

我猜测您的列标题中可能会有一些空格。

Answer 3

从熊猫read_csv文档中可以看到：

header : int or list of ints, default 'infer'
    Row number(s) to use as the column names, and the start of the
    data.  Default behavior is to infer the column names: if no names
    are passed the behavior is identical to ``header=0`` and column
    names are inferred from the first line of the file, if column
    names are passed explicitly then the behavior is identical to
    ``header=None``. Explicitly pass ``header=0`` to be able to
    replace existing names. The header can be a list of integers that
    specify row locations for a multi-index on the columns
    e.g. [0,1,3]. Intervening rows that are not specified will be
    skipped (e.g. 2 in this example is skipped). Note that this
    parameter ignores commented lines and empty lines if
    ``skip_blank_lines=True``, so header=0 denotes the first line of
    data rather than the first line of the file.

这意味着read_csv使用第一行作为标题名称。

使用熊猫将df写入sqlite

3 个答案: