I use psycopg2 to connect to PostgreSQL on Python and I want to use connection pooling.
I don't know what should I do instead commit() and rollback() when I execute INSERT query.
db = pool.SimpleConnectionPool(1, 10,host=conf_hostname,database=conf_dbname,user=conf_dbuser,password=conf_dbpass,port=conf_dbport)
# Get Cursor
#contextmanager
def get_cursor():
con = db.getconn()
try:
yield con.cursor()
finally:
db.putconn(con)
with get_cursor() as cursor:
cursor.execute("INSERT INTO table (fields) VALUES (values) RETURNING id")
id = cursor.fetchone()
I don't get id of inserted record without commit().
UPDATE I can not test the code but I give you some ideas:
You do the commit in connection not in db
# Get Cursor
#contextmanager
def get_cursor():
con = db.getconn()
try:
yield con
finally:
db.putconn(con)
with get_cursor() as cursor:
con.cursor.execute("INSERT INTO table (fields) VALUES (values) RETURNING id")
con.commit()
id = cursor.fetchone()
or
# Get Cursor
#contextmanager
def get_cursor():
con = db.getconn()
try:
yield con.cursor()
con.commit()
finally:
db.putconn(con)
with get_cursor() as cursor:
con.cursor.execute("INSERT INTO table (fields) VALUES (values) RETURNING id")
id = cursor.fetchone()
Connection pooling exist because creating a new connection to a db can be expensive and not to avoid commits or rollbacks. So you can commit your data without any issue, committing data will not destroy the connection.
here is my working example:
db = pool.SimpleConnectionPool(1, 10,host=conf_hostname,database=conf_dbname,user=conf_dbuser,password=conf_dbpass,port=conf_dbport)
#contextmanager
def get_connection():
con = db.getconn()
try:
yield con
finally:
db.putconn(con)
def write_to_db():
with get_connection() as conn:
try:
cursor = conn.cursor()
cursor.execute("INSERT INTO table (fields) VALUES (values) RETURNING id")
id = cursor.fetchone()
cursor.close()
conn.commit()
except:
conn.rollback()
I think this will be a little more pythonic:
db_pool = pool.SimpleConnectionPool(1, 10,
host=CONF.db_host,
database=CONF.db_name,
user=CONF.db_user,
password=CONF.db_user,
port=CONF.db_port)
#contextmanager
def db():
con = db_pool.getconn()
cur = con.cursor()
try:
yield con, cur
finally:
cur.close()
db_pool.putconn(con)
if __name__ == '__main__':
with db() as (connection, cursor):
try:
cursor.execute("""INSERT INTO table (fields)
VALUES (values) RETURNING id""")
my_id = cursor.fetchone()
rowcount = cursor.rowcount
if rowcount == 1:
connection.commit()
else:
connection.rollback()
except psycopg2.Error as error:
print('Database error:', error)
except Exception as ex:
print('General error:', ex)
Related
im using Postgres together with python(psycopg2). Im trying to insert data in a QLabel. It shows the data, but the data comes with clinges. How do I get rid of the clinges?
My code:
def getstunden():
conn = None
try:
conn = psycopg2.connect("dbname=test user=postgres password=test")
cur = conn.cursor()
cur.execute("SELECT stunden FROM ueberstunden WHERE name = 'test'")
row = cur.fetchone()
while row is not None:
self.s_test.setText(str(row))
row = cur.fetchone()
cur.close()
except (Exception, psycopg2.DatabaseError) as error:
print(error)
finally:
if conn is not None:
conn.close()
This is what I get out of it:
I want it to just show 12
Per here Cursor:
Note
cursor objects are iterable, so, instead of calling explicitly fetchone() in a loop, the object itself can be used:
cur.execute("SELECT * FROM test;")
for record in cur:
print record
(1, 100, "abc'def")
(2, None, 'dada')
(3, 42, 'bar')
So to simplify:
def getstunden():
conn = None
try:
conn = psycopg2.connect("dbname=test user=postgres password=test")
cur = conn.cursor()
cur.execute("SELECT stunden FROM ueberstunden WHERE name = 'test'")
for row in cur:
self.s_test.setText(str(row[0]))
cur.close()
except (Exception, psycopg2.DatabaseError) as error:
print(error)
finally:
if conn is not None:
conn.close()
It's just like this
print(row[0])
in your code
def getstunden():
conn = None
try:
conn = psycopg2.connect("dbname=test user=postgres password=test")
cur = conn.cursor()
cur.execute("SELECT stunden FROM ueberstunden WHERE name = 'test'")
row = cur.fetchone()
while row is not None:
#row without the brackets
self.s_test.setText(str(row[0]))
row = cur.fetchone()
cur.close()
except (Exception, psycopg2.DatabaseError) as error:
print(error)
finally:
if conn is not None:
conn.close()
i'm taking data from textfile which contains some duplicate data.And i'm trying to insert them into database without duplicating.i'm in trouble where inserting duplicate data.it should not be inserted again.data are not static values.
text_file = open(min_file, "r")
#doc = text_file.readlines()
for line in text_file:
field = line.split(";")
print(field)
try:
connection = mysql.connector.connect(host='localhost',
database='testing',
user='root',
password='root')
if connection.is_connected():
db_Info = connection.get_server_info()
print("Connected to MySQL Server version ", db_Info)
cursor = connection.cursor()
cursor.execute("select database();")
record = cursor.fetchone()
print("You're connected to database: ", record)
mycursor = connection.cursor()
#before inserting
mycursor.execute("Select * from ftp")
myresult = mycursor.fetchall()
for i in myresult:
print(i)
sql ="Insert into ftp(a,b,c,d) \
select * from( Select VALUES(%s,%s,%s,%s) as temp \
where not exists \
(Select a from ftp where a = %s) LIMIT 1"
mycursor.execute(sql,field)
print(mycursor.rowcount, "record inserted.")
connection.commit()
except Error as e:
print("Error while connecting to MySQL", e)
finally:
if connection.is_connected():
cursor.close()
connection.close()
print("MySQL connection is closed")
One option is to add Unique constraint and let the DB validate uniqueness, this will throw exception which you can catch and skip.
I've already tried adding in a comma after Name and the question mark in "VALUES" and was getting a syntax error for my parthenthesis.
#app.route("/Disease/new", methods = ["POST"])
def addDisease():
newDisease = {}
conn = None
try:
jsonPostData = request.get_json()
Name = jsonPostData["Name"]
conn = sqlite3.connect("./dbs/ContactTracer.db")
conn.row_factory = sqlite3.Row
sql = """
INSERT INTO Disease(Name) VALUES(?)
"""
cursor = conn.cursor()
cursor.execute(sql, (Name))
conn.commit()
sql = """
SELECT Disease.ID, Disease.Name
From Disease
Where Disease.ID = ?
"""
cursor.execute(sql,(cursor.lastrowid,))
row = cursor.fetchone()
newDisease["ID"] = row["ID"]
newDisease["Name"] = row["Name"]
except Error as e:
print(f"Error opening the database{e}")
abort(500)
finally:
if conn:
conn.close()
return newDisease
Remove the () and check if INSERT succeeded
cursor.execute(sql, Name)
...
if cursor.lastrowid:
cursor.execute(sql, cursor.lastrowid)
I am new in mysql, I have a table with two cols tag_id and time_stamp, I use a python connector. I need to insert new tag_id just only if did not insert the same tag_id in last 5 min (or some other duration). How can I do that using python mysql.connector?
create table:
import mysql.connector
from mysql.connector import Error
try:
connection = mysql.connector.connect(host='localhost',
database='test',
user='root',
password='root')
mySql_Create_Table_Query = """CREATE TABLE tags (
Id int(11) NOT NULL AUTO_INCREMENT,
tag_id varchar(250) NOT NULL,
time_stamp Datetime NOT NULL,
PRIMARY KEY (Id)) """
cursor = connection.cursor()
result = cursor.execute(mySql_Create_Table_Query)
print("Laptop Table created successfully ")
except mysql.connector.Error as error:
print("Failed to create table in MySQL: {}".format(error))
finally:
if (connection.is_connected()):
cursor.close()
connection.close()
print("MySQL connection is closed")
Insertion function:
def insertVariblesIntoTable(tag, time_stamp):
try:
connection = mysql.connector.connect(host='localhost',
database='test',
user='root',
password='root')
cursor = connection.cursor()
mySql_insert_query = """INSERT INTO tags(tag_id, time_stamp )
VALUES (%s, %s) """
recordTuple = (tag, time_stamp)
cursor.execute(mySql_insert_query, recordTuple)
connection.commit()
print("Record inserted successfully into tags table")
except mysql.connector.Error as error:
print("Failed to insert into MySQL table {}".format(error))
finally:
if (connection.is_connected()):
cursor.close()
connection.close()
print("MySQL connection is closed")
I'd just do a query of the table like this:
import arrow
check = '''select max(timestamp) from tags where tag_id = {}'''
try:
with conn.cursor() as curs:
curs.execute(check.format(tag_id))
max_time = curs.fetchone()
if max_time <= arrow.utcnow().shift(minutes=-5).format('YYYY-MM-DD HH:mm:ss'):
#run the inserts
else:
pass
I am trying to retrieve all rows in mysql.
import mysql.connector,sys
user,pw, host,db = 'root','12345','127.0.0.1','CA2Database'
cnx = mysql.connector.connect(user=user, password=pw, host=host, database=db)
cursor = cnx.cursor()
try:
print(cursor.execute('SELECT * FROM student'))
except mysql.connector.Error as err:
print(err)
print("Error Code:", err.errno)
print("SQLSTATE", err.sqlstate)
print("Message", err.msg)
finally:
print()
The output is None . There is data in the table.
https://imgur.com/a/APUuZot
Probably you were missing some necessary function calls. This should do:
user,pw, host,db = 'root','12345','127.0.0.1','CA2Database'
cnx = mysql.connector.connect(user=user, password=pw, host=host, database=db)
cursor = cnx.cursor()
sql_query = 'SELECT * FROM student;'
cursor.execute(sql_query)
data = cursor.fetchall()
cnx.commit()
cursor.close()