import sqlite3
conn = sqlite3.connect("test.db")
cursor = conn.cursor()
It should create the database, but it does not. Any help?
This code will create an sqlite db file called "test.db" in the same directory you are running your script from.
For example, if you have your python file in:
/home/user/python_code/mycode.py
And you run it from:
/home/user/
With:
python python_code/mycode.py # or python3
It will create an "empty" sqlite db file at
/home/user/test.db
If you can't find the test.db file, make sure you pass it the full path of where you want it to be located.
i.e.
conn = sqlite3.connect("/full/path/to/location/you/want/test.db")
I had the same problem, my .db file wasn't appearing because I forgot to add test.db at the end of path, see line 2 below
import sqlite3
databaseFile = "/home/user/test.db" #don't forget the test.db
conn = sqlite3.connect(databaseFile)
cursor = conn.cursor()
I suspect the DB will not be created on disk until you create at least one table in it. Just calling conn.cursor() is not sufficient.
Console sqlite3 utility behaves this way, too.
Related
I have a .sql file which I'm trying to load in an online Python environment (JupyterHub) but other code I've found online has just left me confused. I've gotten as far as:
import sqlite3
from sqlite3 import connect
sqlite_uri = "sqlite:///basketball.db"
sqlite_engine = sqlalchemy.create_engine(sqlite_uri)
connection = sqlite3.connect(":memory:")
cursor = connection.cursor()
sql_file = open("travel-times.sql")
travel = sql_file.read()
travel
sql_expr = """
SELECT *
FROM travel;
"""
pd.read_sql(sql_expr, sqlite_engine)
and calling the 'travel' object does at least print the data in raw form, but from there I'm at a loss to actually load the table from here. What commands would accomplish this?
The title is pretty self explanotory.
I've tried the following code :
import _mssql
conn = _mssql.connect(server='', user='', password='', database='')
conn.execute_non_query("IF EXISTS (SELECT 0 FROM sys.databases WHERE name = 'mydb') BEGIN ALTER DATABASE mydb MODIFY NAME = mydb_old END")
conn.execute_non_query("RESTORE DATABASE mydb FROM DISK='C:\mydb.bak'")
But I get the following error : No module named '_mssql'.
I have the version 2.2.2 of pymssql and I use Python 3.9.
I'm just trying to write and read from this database, and I only have the .bak file. I'm quite new to SQL, so I might be doing it the wrong way ? I only have a .bak file though, nothing else.
Thank you for your time.
As mentioned in the comments:
MySQL <> MS SQL
And I have to fill the server = "", user = "", etc ...
Writing a script to convert raw data for MySQL import I worked with a temporary textfile so far which I later imported manually using the LOAD DATA INFILE... command.
Now I included the import command into the python script:
db = mysql.connector.connect(user='root', password='root',
host='localhost',
database='myDB')
cursor = db.cursor()
query = """
LOAD DATA INFILE 'temp.txt' INTO TABLE myDB.values
FIELDS TERMINATED BY ',' LINES TERMINATED BY ';';
"""
cursor.execute(query)
cursor.close()
db.commit()
db.close()
This works but temp.txt has to be in the database directory which isn't suitable for my needs.
Next approch is dumping the file and commiting directly:
db = mysql.connector.connect(user='root', password='root',
host='localhost',
database='myDB')
sql = "INSERT INTO values(`timestamp`,`id`,`value`,`status`) VALUES(%s,%s,%s,%s)"
cursor=db.cursor()
for line in lines:
mode, year, julian, time, *values = line.split(",")
del values[5]
date = datetime.strptime(year+julian, "%Y%j").strftime("%Y-%m-%d")
time = datetime.strptime(time.rjust(4, "0"), "%H%M" ).strftime("%H:%M:%S")
timestamp = "%s %s" % (date, time)
for i, value in enumerate(values[:20], 1):
args = (timestamp,str(i+28),value, mode)
cursor.execute(sql,args)
db.commit()
Works as well but takes around four times as long which is too much. (The same for construct was used in the first version to generate temp.txt)
My conclusion is that I need a file and the LOAD DATA INFILE command to be faster. To be free where the textfile is placed the LOCAL option seems useful. But with MySQL Connector (1.1.7) there is the known error:
mysql.connector.errors.ProgrammingError: 1148 (42000): The used command is not allowed with this MySQL version
So far I've seen that using MySQLdb instead of MySQL Connector can be a workaround. Activity on MySQLdb however seems low and Python 3.3 support will probably never come.
Is LOAD DATA LOCAL INFILE the way to go and if so is there a working connector for python 3.3 available?
EDIT: After development the database will run on a server, script on a client.
I may have missed something important, but can't you just specify the full filename in the first chunk of code?
LOAD DATA INFILE '/full/path/to/temp.txt'
Note the path must be a path on the server.
To use LOAD DATA INFILE with every accessible file you have to set the
LOCAL_FILES client flag while creating the connection
import mysql.connector
from mysql.connector.constants import ClientFlag
db = mysql.connector.connect(client_flags=[ClientFlag.LOCAL_FILES], <other arguments>)
I wrote a Python script which initializes an empty database if it doesn't exist.
import os
if not os.path.exists('Database'):
os.makedirs('Database')
os.system('sqlite3 Database/testDB.db ";"')
# rest of the script...
Can I do this in a more Pythonic fashion, with a try-except, or is this kind of code acceptable?
I think you can do it like this:
import sqlite3
conn = sqlite3.connect('Database/testDB.db')
This should connect to your database and create it in case that it doesn't exist. I'm not sure this is the most pythonic way, but it does use the sqlite3 module instead of the sqlite3 command.
Making it Pythonic: create a sqlite3 database if it doesn't exist?
The most Pythonic way to do this is to use the context manager:
import sqlite3
# if we error, we rollback automatically, else commit!
with sqlite3.connect('/Temp/testDB.db') as conn:
cursor = conn.cursor()
cursor.execute('SELECT SQLITE_VERSION()')
data = cursor.fetchone()
print('SQLite version:', data)
In a python shell this echoes for me:
<sqlite3.Cursor object at 0x0CCAD4D0>
SQLite version: (u'3.5.9',)
To ensure you have a tempfile path that works across platforms, use tempfile.gettempdir:
import tempfile
with sqlite3.connect(tempfile.gettempdir() + '/testDB.db') as conn:
...
Create directory path, database file and table
Here is a recipe to create the directory path, database file and table
when necessary. If these already exist, the script will overwrite nothing and simply use what is at hand.
import os
import sqlite3
data_path = './really/deep/data/path/'
filename = 'whatever'
os.makedirs(data_path, exist_ok=True)
db = sqlite3.connect(data_path + filename + '.sqlite3')
db.execute('CREATE TABLE IF NOT EXISTS TableName (id INTEGER PRIMARY KEY, quantity INTEGER)')
db.close()
sqlite3.connect will attempt to create a database if it doesn't exist - so the only way to tell if one does exist is to try to open it and catch an IOError. Then to create a blank database, just connect using the sqlite3 module.
import sqlite3
try:
open('idonotexist')
print 'Database already exists!'
except IOError as e:
if e.args == 2: # No such file or directory
blank_db = sqlite3.connect('idontexist')
print 'Blank database created'
else: # permission denied or something else?
print e
Of course, you may still have to do something with os.makedirs depending on if the structure already exists.
I'm trying to modify the two database files used by Google Drive to redirect my sync folder via a script (snapshot.db and sync_conf.db). While I can open the files in certain sqlite browsers (not all) I cant get python to execute a query. I just get the message: sqlite3.DatabaseError: file is encrypted or is not a database
Apparently google is using a Write-Ahead-logging (WAL) configuration on the databases and it can be turned off by running PRAGMA journal_mode=DELETE; (according to sqlite.org) against the database, but I can't figure out how to run that against the database if python can't read it.
heres what I have (I tried executing the PRAGMA command and commiting and then reopening but it didnt work):
import sqlite3
snapShot = 'C:\Documents and Settings\user\Local Settings\Application Data\Google\Drive\snapshot.db'
sync_conf = 'C:\Documents and Settings\user\Local Settings\Application Data\Google\Drive\sync_config.db'
sync_folder_path = 'H:\Google Drive'
conn = sqlite3.connect(snapShot)
cursor = conn.cursor()
#cursor.execute('PRAGMA journal_mode=DELETE;')
#conn.commit()
#conn= sqlite3.connect(snapShot)
#cursor = conn.cursor()
query = "UPDATE local_entry SET filename = '\\?\\" + sync_folder_path +"' WHERE filename ='\\?\C:Users\\admin\Google Drive'"
print query
cursor.execute(query)
problem solved. I just downloaded the latest version of sqlite from http://www.sqlite.org/download.html and overwrote the old .dll in my python27/DLL directory. Works fine now.
What a nusance.
I don't think the journal_mode pragma should keep sqlite3 from being able to open the db at all. Perhaps you're using an excessively old version of the sqlite3 lib? What version of Python are you using, and what version of the sqlite3 library?
import sqlite3
print sqlite3.version