MySQLdb: Pandas data-frame to SQL database error: not all arguments converted during string formatting

Question

So, I wanted to move a dataframe to a database into a table but I am encountering a few problems. I made the dataframe using the pandas library and wanted to upload the data into a table in my database.

Relevant snippets of my Code and the error details are as follows:

#CONNECTION TO SQL DATABASE
db=sql.connect(host="localhost",user="root",passwd="password",db="database_name")
cur=db.cursor()
#CONVERTING DATAFRAME(df_final) INTO TABLE
df_final.to_sql(con=db, name='finaltable', if_exists='replace', chunksize=5000)

Error details:

Traceback (most recent call last):
File "C:\Users\DELL\AppData\Local\Programs\Python\Python36\lib\site-packages\M
ySQLdb\cursors.py", line 238, in execute
query = query % args
TypeError: not all arguments converted during string formatting

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "C:\Users\DELL\AppData\Local\Programs\Python\Python36\lib\site-packages\p
andas\io\sql.py", line 1400, in execute
cur.execute(*args)
File "C:\Users\DELL\AppData\Local\Programs\Python\Python36\lib\site-packages\M
ySQLdb\cursors.py", line 240, in execute
self.errorhandler(self, ProgrammingError, str(m))
File "C:\Users\DELL\AppData\Local\Programs\Python\Python36\lib\site-packages\M
ySQLdb\connections.py", line 52, in defaulterrorhandler
raise errorclass(errorvalue)
_mysql_exceptions.ProgrammingError: not all arguments converted during string fo
rmatting

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "pt.py", line 77, in <module>
df_final.to_sql(con=db, name='finaltable', if_exists='replace', chunksize=50
00)
File "C:\Users\DELL\AppData\Local\Programs\Python\Python36\lib\site-packages\p
andas\core\generic.py", line 2127, in to_sql
dtype=dtype)
File "C:\Users\DELL\AppData\Local\Programs\Python\Python36\lib\site-packages\p
andas\io\sql.py", line 450, in to_sql
chunksize=chunksize, dtype=dtype)
File "C:\Users\DELL\AppData\Local\Programs\Python\Python36\lib\site-packages\p
andas\io\sql.py", line 1502, in to_sql
table.create()
File "C:\Users\DELL\AppData\Local\Programs\Python\Python36\lib\site-packages\p
andas\io\sql.py", line 561, in create
if self.exists():
File "C:\Users\DELL\AppData\Local\Programs\Python\Python36\lib\site-packages\p
andas\io\sql.py", line 549, in exists
return self.pd_sql.has_table(self.name, self.schema)
File "C:\Users\DELL\AppData\Local\Programs\Python\Python36\lib\site-packages\p
andas\io\sql.py", line 1514, in has_table
return len(self.execute(query, [name, ]).fetchall()) > 0
File "C:\Users\DELL\AppData\Local\Programs\Python\Python36\lib\site-packages\p
andas\io\sql.py", line 1412, in execute
raise_with_traceback(ex)
File "C:\Users\DELL\AppData\Local\Programs\Python\Python36\lib\site-packages\p
andas\compat\__init__.py", line 403, in raise_with_traceback
raise exc.with_traceback(traceback)
File "C:\Users\DELL\AppData\Local\Programs\Python\Python36\lib\site-packages\p
andas\io\sql.py", line 1400, in execute
cur.execute(*args)
File "C:\Users\DELL\AppData\Local\Programs\Python\Python36\lib\site-packages\M
ySQLdb\cursors.py", line 240, in execute
self.errorhandler(self, ProgrammingError, str(m))
File "C:\Users\DELL\AppData\Local\Programs\Python\Python36\lib\site-packages\M
ySQLdb\connections.py", line 52, in defaulterrorhandler
raise errorclass(errorvalue)
pandas.io.sql.DatabaseError: Execution failed on sql 'SELECT name FROM 
sqlite_ma
ster WHERE type='table' AND name=?;': not all arguments converted during string
formatting

Hrithik Diwakar · Accepted Answer · 2018-06-13 09:23:33Z

1

So apparently my approach has gone obsolete due to updates and therefore for the connection bit, I used 'create_engine' from 'sqlalchemy' library instead of 'mysqldb.connect()' to access the database:

#relevant import:
from sqlalchemy import create_engine

#accessing database:
engine = create_engine("mysql://root:PASSWORD@host/database_name")
con = engine.connect()

#uploading dataframe to database:
df.to_sql(con=con, name='final_table', if_exists='replace', chunksize=10000)

answered Jun 13, 2018 at 9:23

Hrithik Diwakar

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Lyubomir Angelov · Accepted Answer · 2018-06-12 18:59:07Z

0

For me, it seems that you have nulls in the data. Try to fill the nulls in the dataframe before calling .to_sql()

df_final.fillna('default string')

Or to remove the null rows

df_final.dropna(inplace=True)

answered Jun 12, 2018 at 18:59

Lyubomir Angelov

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