Pandas の内容で sqlite テーブルを上書きしようとすると、Pandas はテーブルを上書きしますdataframe
がDROP
、INSERT
.
最小限の作業例を次に示します。
import sqlite3 as sq
import pandas as pd
import pandas.io.sql as pd_sql
d = pd.DataFrame({'year':[2008,2008,2008,2008,2009,2009,2009,2009],
'flavour':['strawberry','strawberry','banana','banana',
'strawberry','strawberry','banana','banana'],
'day':['sat','sun','sat','sun','sat','sun','sat','sun'],
'sales':[10,12,22,23,11,13,23,24]})
# Connect to the database (create if necessary)
conn = sq.connect('mydb')
# Create the table 'mytable' if necessary
if not pd_sql.table_exists('mytable', conn, 'sqlite'):
pd_sql.write_frame(d, 'mytable', conn)
# Change some data
d['sales'][d.sales==24] = 25
# Confirm the table exists
print "Table 'mytable' exists:"
print pd_sql.table_exists('mytable', conn, 'sqlite')
# Get some data from the table
cur = pd_sql.execute("SELECT DISTINCT flavour FROM mytable", conn)
print "Here's the data to prove the table exists:"
print cur.fetchall()
try:
print "Attempting write_frame..."
pd_sql.write_frame(d, 'mytable', conn, if_exists='replace')
except sq.OperationalError as e:
print "sq.OperationalError is: " + str(e)
print pd_sql.table_exists('mytable', conn, 'sqlite')
conn.close()
このスクリプトを実行すると、次の出力が得られます。
Table 'mytable' exists:
True
Here's the data to prove the table exists:
[(u'banana',), (u'strawberry',)]
Attempting write_frame...
sq.OperationalError is: no such table: mytable
Table 'mytable' exists after write_frame:
False
これはパンダのバグのようです。誰でもこれを確認できますか?
いつもありがとう、ロブ