conn = sqlite3.connect('./mydb.db')
c = conn.cursor()
with open('./mydb_tmp.sql', 'w') as f:
for row in c.execute('SELECT * FROM FLOWS'):
print >>f, row
c.execute('DELETE FROM FLOWS;')
conn.close()
After that, all rows are still in mydb
You need to commit the command.
conn = sqlite3.connect('./mydb.db')
c = conn.cursor()
with open('./mydb_tmp.sql', 'w') as f:
for row in c.execute('SELECT * FROM FLOWS'):
print >>f, row
c.execute('DELETE FROM FLOWS;')
# Flush your commands to the db with conn.commit().
conn.commit()
conn.close()
Check the documentation : https://docs.python.org/2/library/sqlite3.html
Related
After the DatabaseError is catched (try-except block) the previous data in the table is deleted. I cannot figure out this strange behaviour.
this is the code I used
def copy_from_stringio(df, table):
conn = None
try:
# read database configuration
params = config()
# connect to the PostgreSQL database
conn = psycopg2.connect(**params)
# create a new cursor
cur = conn.cursor()
# save dataframe to an in memory buffer
buffer = StringIO()
df.to_csv(buffer, index=False, header=False,sep=';')
buffer.seek(0)
#cursor = conn.cursor()
cur.copy_from(buffer, table, sep=";")
conn.commit()
print("copy_from_stringio() done")
cur.close()
except (Exception, psycopg2.DatabaseError) as error:
print(error)
finally:
if conn is not None:
conn.close()
# Module Imports
import mariadb
import sys
import csv
from pathlib import Path
def connect_to_mariaDB(databse, user, passwd):
# Connect to MariaDB Platform
try: conn = mariadb.connect(
user=user,
password=passwd,
host="localhost",
port=3306,
database=databse
)
except mariadb.Error as e:
print(f"Error connecting to MariaDB Platform: {e}")
sys.exit(1)
return conn
def check_if_table_exists_and_overwrite(conn, tableName, database, overwrite):
cur = conn.cursor()
cur.execute(f"SELECT table_name FROM information_schema.tables WHERE table_schema = '{database}';")
for(table_name) in cur:
if table_name[0] == tableName:
if overwrite == "YES":
print("table exists - DROP TABLE")
cur.execute(f"DROP TABLE {tableName}")
return True
else:
return False
return True
def import_file_into_db_table_(
filename, database, user, passwd, tableName,
create_table_statement = "", overwrite = False):
conn = connect_to_mariaDB(database, user, passwd)
cur = conn.cursor()
if conn != None:
print(f"Connection successful to database {database}")
if check_if_table_exists_and_overwrite(conn, tableName, database, overwrite):
cur.execute(create_table_statement)
print("table is created")
path = f"{Path().absolute()}\\{filename}".replace("\\","/")
print(path)
load_data_statement = f"""LOAD DATA INFILE '{path}'
INTO TABLE {tableName}
FIELDS TERMINATED BY ';'
OPTIONALLY ENCLOSED BY '\"'
LINES TERMINATED BY '\\n'
IGNORE 1 LINES
"""
print(load_data_statement)
cur.execute(load_data_statement)
print("load data into table - successful")
else:
print("table exists - no permission to overwrite")
cur.execute("SELECT * FROM student_mat;")
for da in cur:
print(da)
# variables
filename = "student-mat.csv"
database = "dbs2021"
tableName = "student_mat"
# load the create_table_statement
create_table_statement = ""
path = f"{Path().absolute()}\\create_table_statement.txt"
with open(path, newline='') as file:
spamreader = csv.reader(file, delimiter='\n', quotechar='|')
for row in spamreader:
create_table_statement += row[0]
parameters_length = len(sys.argv)
if parameters_length == 3:
user, passwd = sys.argv[1], sys.argv[2]
import_file_into_db_table_(filename, database, user, passwd, tableName, create_table_statement, "YES")
elif parameters_length == 4:
user, passwd, overwrite = sys.argv[1], sys.argv[2], sys.argv[3]
import_file_into_db_table_(filename, database, user, passwd, tableName, create_table_statement, overwrite)
else:
print("wrong parameters\nTry -user -passwd or additional -overwrite")
The code checks if there is a table with the same name in the db and then potentially drops it, creates a new table and loads the data of the csv file into the table.
When executing the code it seems like everything is working but when going in the mariadb command prompt the created table is empty even though when outputting the table in the code it is filled.
By default MariaDB Connector/Python doesn't use autocommit mode.
You need either set autocommit=True when establishing the connection or you have to commit your changes with conn.commit().
I have a table in SQLite 3 as follows and I am planning on using it to store a variety of files: txt, pdf, images and zip files.
CREATE TABLE zip (filename TEXT PRIMARYKEY NOT NULL, zipfile BLOB NOT NULL);
To store and retrieve I am experimenting with the following python code
#!env/bin/python
import sqlite3 as lite
import os
import sys
def insertfile(_filename):
try:
con = lite.connect('histogram.db', detect_types=lite.PARSE_DECLTYPES)
con.row_factory = lite.Row
cur = con.cursor()
cur.execute('PRAGMA foreign_keys=ON;')
_f = open(_filename,'rb')
_split = os.path.split(_filename)
_file = _split[1]
_blob = _f.read()
cur.execute('INSERT INTO zip (filename,zipfile) VALUES (?,?)', (_file,lite.Binary(_blob)))
_f.close()
con.commit()
cur.close()
con.close()
except Exception as ex:
print ex
def getfile(_filename):
try:
con = lite.connect('histogram.db', detect_types=lite.PARSE_DECLTYPES)
con.row_factory = lite.Row
cur = con.cursor()
cur.execute('PRAGMA foreign_keys=ON;')
cur.execute('SELECT zipfile from zip where filename = ?', (_filename,))
_files = cur.fetchall()
if len(_files) > 0:
_file = open('Test/'+ _filename,'wb')
_file.write(_files[0]['zipfile'])
_file.close()
cur.close()
con.close()
except Exception as ex:
print ex
if __name__ == '__main__':
print 'works'
insertfile(sys.argv[1])
getfile(os.path.split(sys.argv[1])[1])
When I test this on files like .txt, .py, .pdf etc., it works fine.
With Zip files, there is no error while storing into the table but an error while retrieving the file:
Could not decode to UTF-8 column 'zipfile' with text 'PK '
There seems to be some encoding or decoding issue.
I basically tried using the code from one of the questions
Insert binary file in SQLite database with Python
.
It worked originally for the pdf, png, jpg files. But I was still getting the error for Zip files. When I commented out the insertion and just ran the retrieval code it worked. Now the code below works.
def insertfile(_filename):
try:
con = lite.connect('histogram.db', detect_types=lite.PARSE_DECLTYPES)
con.row_factory = lite.Row
cur = con.cursor()
cur.execute('PRAGMA foreign_keys=ON;')
_f = open(_filename,'rb')
_split = os.path.split(_filename)
_file = _split[1]
_blob = _f.read()
cur.execute('INSERT INTO zip (filename,zipfile) VALUES (?,?)', (_file,lite.Binary(_blob)))
_f.close()
con.commit()
cur.close()
con.close()
except Exception as ex:
print ex
def getfile(_filename):
try:
con = lite.connect('histogram.db', detect_types=lite.PARSE_DECLTYPES)
con.row_factory = lite.Row
cur = con.cursor()
cur.execute('PRAGMA foreign_keys=ON;')
cur.execute('SELECT zipfile from zip where filename = ?', (_filename,))
_files = cur.fetchall()
if len(_files) > 0:
_file = open('Downloads/'+ _filename,'wb')
_file.write(_files[0]['zipfile'])
_file.close()
cur.close()
con.close()
except Exception as ex:
print ex
if __name__ == '__main__':
print 'works'
insertfile(sys.argv[1])
getfile(os.path.split(sys.argv[1])[1])
I need python script for display sql query with nice output and readable this not readable for heavy tables...
cnx = mysql.connector.connect(user='root', password='*****',
host='127.0.0.1',
database='dietetique')
c = cnx.cursor()
sys.stdout = open('mysql_data.log', 'w')
c.execute("SELECT * FROM administrations;")
for row in c:
print row
import pypyodbc
ID=2
ConnectionDtl='Driver={SQL Server};Server=WIN7-297;Database=AdventureWorks2014;trusted_connection=yes'
connection = pypyodbc.connect(ConnectionDtl)
print("Retrieve row based on [FirstName]='Mani'")
cursor = connection.cursor()
SQLCommand = ("SELECT [FirstName],[LastName] "
"FROM Person.SampleData "
"WHERE FirstName =?")
Values = ['Mani']
print(SQLCommand)
cursor.execute(SQLCommand,Values)
i=1
for x in cursor :
row = cursor.fetchone()
print str(i) + ". FirstName: " + row[0] + " LastName: " + row[1]
i=i+1
connection.close()
you can execute the same code just by adding limits to the Sql Query.
cnx = mysql.connector.connect(user='root', password='*****',
host='127.0.0.1',
database='dietetique')
c = cnx.cursor()
sys.stdout = open('mysql_data.log', 'w')
limitvalue=1000
for offsetvalue in range(0 , maximum_rows_you_want,1000):
c.execute("SELECT * FROM administrations limit "+ limitvalue + " offset " + offsetvalue +";")
for row in c:
print row
I'm trying to create a python script that will copy a glob result into postgres. This is what I have:
import psycopg2, glob
sitesizetemp = glob.glob('C:/Data/Sheltered BLPUs/CSVs/sitesize*.csv')
conn = psycopg2.connect("dbname=postgres user=postgres")
cur = conn.cursor()
cur.execute("COPY sitesize FROM" sitesizetemp "DELIMITER ',' CSV;")
conn.commit()
cur.close()
conn.close()
I'm pretty new to all of this so any help is very welcome! thanks
import psycopg2, glob
sitesizetemp = glob.glob('C:/Data/Sheltered BLPUs/CSVs/sitesize*.csv')
conn = psycopg2.connect("dbname=postgres user=postgres")
cur = conn.cursor()
for f in sitesizetemp:
cur.execute("COPY sitesize FROM '%s' DELIMITER ',' CSV;" % f)
conn.commit()
cur.close()
conn.close()