best way to access and close a postgres database using python dataset

Using such a data store can be important for quick and reliable data access. The database is readily set up on my local computer and accessed from Python using the SQLAlchemy library. Pandas and SQLAlchemy work well together to ingest the dataset into the PostgreSQL database in merely a few lines of code, thus saving a lot of time and nerves. , 1 week ago Jul 09, 2019  · Create a Table in the Database. The next step is to create a table in the database to import the data into. Create a database: $ createdb -O haki testload. Change haki in the example to your local user. To connect from Python to a PostgreSQL database, we use psycopg: $ python -m pip install psycopg2. , The database.ini file would be included in the .gitignore file to protect the author’s password. Once you connect to the PostgreSQL database you can query the data necessary for your analysis. The results of the query can be displayed in a Pandas data frame which can then be operated on like all data stored in Pandas. , 5 days ago Apr 23, 2018  · This is mostly used to create databases, which we will create using the following command: create database sample_db; Then, we connect to the database we just created using PSequel. We’ll open PSequel and enter the name’s database, in our case: sample_db . Click on “Connect” to connect to the database.

import dataset from sqlalchemy.pool
import NullPool db = dataset.connect(path_database, engine_kwargs = {
   'poolclass': NullPool
}) table_f1 = db['name_table'] # Do operations on table_f1 db.commit() db.executable.close()

import datasetfrom sqlalchemy.pool
import NullPool db = dataset.connect(path_database, engine_kwargs = {
   'poolclass': NullPool
}) table_f1 = db['name_table'] # Do operations on table_f1 db.commit() db.executable.close()

import datasetfrom sqlalchemy.pool
import NullPool with dataset.connect(path_database, engine_kwargs = {
   'poolclass': NullPool
}) as db: table_f1 = db['name_table'] # Do operations on table_f1db.commit()

import datasetfrom sqlalchemy.pool
import NullPool with dataset.connect(path_database, engine_kwargs = {
   'poolclass': NullPool
}) as db: table_f1 = db['name_table'] print(db.local.conn.closed) # >>> False # Do operations on table_f1 # end of the context manager, trying to commit db.executable.close() print(db.local.conn.closed) # >>> True

# db['name_table'].all() == > throws an error due to closed connection

# db['new_table'] == > enough to add a new table

PostgreSQL provides its own shell to execute queries. To establish connection with the PostgreSQL database, make sure that you have installed it properly in your system. Open the PostgreSQL shell prompt and pass details like Server, Database, username, and password. If all the details you have given are appropriate, a connection is established with PostgreSQL database.,The following Python code shows how to connect to an existing database. If the database does not exist, then it will be created and finally a database object will be returned. The name of the default database of PostgreSQL is postrgre. Therefore, we are supplying it as the database name.,The connection class of the psycopg2 represents/handles an instance of a connection. You can create new connections using the connect() function. This accepts the basic connection parameters such as dbname, user, password, host, port and returns a connection object. Using this function, you can establish a connection with the PostgreSQL.,While passing the details you can go with the default server, database, port and, user name suggested by the shell.

import psycopg2

#establishing the connection
conn = psycopg2.connect(
   database = "postgres", user = 'postgres', password = 'password', host = '127.0.0.1', port = '5432'
)
#Creating a cursor object using the cursor() method
cursor = conn.cursor()

#Executing an MYSQL
function using the execute() method
cursor.execute("select version()")

# Fetch a single row using fetchone() method.
data = cursor.fetchone()
print("Connection established to: ", data)

#Closing the connection
conn.close()
Connection established to: (
   'PostgreSQL 11.5, compiled by Visual C++ build 1914, 64-bit',
)

Connection established to: (
   'PostgreSQL 11.5, compiled by Visual C++ build 1914, 64-bit',
)