How to write a simple toy database in Python

How to write a simple toy database in Python

How to write a simple toy database in Python: MySQL, PostgreSQL, Oracle, Redis, and many more, you just name it — databases are a really important piece of technology in the progress of human civilization. Today we can see how valuable data are, and so keeping them safe and stable is where the database comes in!

How to write a simple toy database in Python: MySQL, PostgreSQL, Oracle, Redis, and many more, you just name it — databases are a really important piece of technology in the progress of human civilization. Today we can see how valuable data are, and so keeping them safe and stable is where the database comes in!

So we can see how important databases are as well. For a quite some time I was thinking of creating My Own Toy Database just to understand, play around, and experiment with it. As Richard Feynman said:

“What I cannot create, I do not understand.”
So without any further talking let’s jump into the fun part: coding.

Let’s Start Coding…

For this Toy Database, we’ll use Python (my favorite ❤️). I named this database FooBarDB (I couldn’t find any other name 😉), but you can call it whatever you want!

So first let’s import some necessary Python libraries which are already available in Python Standard Library:

import json
import os

Yes, we only need these two libraries! We need json as our database will be based on JSON, and os for some path related stuff.

Now let’s define the main class FoobarDB with some pretty basic functions, which I’ll explain below.

class FoobarDB(object):
    def __init__(self , location):
        self.location = os.path.expanduser(location)
        self.load(self.location)

    def load(self , location):
        if os.path.exists(location):
            self._load()
        else:
            self.db = {}
        return True

    def _load(self):
        self.db = json.load(open(self.location , "r"))

    def dumpdb(self):
        try:
            json.dump(self.db , open(self.location, "w+"))
            return True
        except:
            return False

Here we defined our main class with an __init__ function. Whenever creating a Foobar Database we only need to pass the location of the database. In the first __init__ function we take the location parameter and replace ~ or ~user with user’s home directory to make it work intended way. And finally, put it in self.location variable to access it later on the same class functions. In the end, we are calling the load function passing self.location as an argument.

. . . .
    def load(self , location):
        if os.path.exists(location):
            self._load()
        else:
            self.db = {}
        return True
. . . .

In the next load function we take the location of the database as a param. Then check if the database exists or not. If it exists, we load it with the _load() function (explained below). Otherwise, we create an empty in-memory JSON object. And finally, return true on success.

. . . . 

    def _load(self):
        self.db = json.load(open(self.location , "r"))
. . . .

In the _load function, we just simply open the database file from the location stored in self.location. Then we transform it into a JSON object and load it into self.db variable.

 def dumpdb(self):
        try:
            json.dump(self.db , open(self.location, "w+"))
            return True
        except:
            return False

And finally, the dumpdb function: its name says what it does. It takes the in-memory database (actually a JSON object) from the self.db variable and saves it in the database file! It returns True if saved successfully, otherwise returns False.

Make It a Little More Usable… 😉

Wait a minute! 😐 A database is useless if it can’t store and retrieve data, isn’t it? Let’s go and add them also…😎

def set(self , key , value):
        try:
            self.db[str(key)] = value
            self.dumpdb()
            return True
        except Exception as e:
            print("[X] Error Saving Values to Database : " + str(e))
            return False

    def get(self , key):
        try:
            return self.db[key]
        except KeyError:
            print("No Value Can Be Found for " + str(key))  
            return False

    def delete(self , key):
        if not key in self.db:
            return False
        del self.db[key]
        self.dumpdb()
        return True

The set function is to add data to the database. As our database is a simple key-value based database, we’ll only take a key and value as an argument.

First, we’ll try to add the key and value to the database and then save the database. If everything goes right it will return True. Otherwise, it will print an error message and return False. (We don’t want it to crash and erase our data every time an error occurs 😎).

def get(self, key):
        try:
            return self.db[key]
        except KeyError:
            return False

get is a simple function, we take key as an argument and try to return the value linked to the key from the database. Otherwise False is returned with a message.

		def delete(self , key):
        if not key in self.db:
            return False
        del self.db[key]
        self.dumpdb()
        return True

delete function is to delete a key as well as its value from the database. First, we make sure the key is present in the database. If not we return False. Otherwise, we delete the key with the built-in del which automatically deletes the value of the key. Next, we save the database and it returns false.

Now you might think, what if I’ve created a large database and want to reset it? In theory, we can use delete — but it’s not practical, and it’s also very time-consuming! ⏳ So we can create a function to do this task…

    def resetdb(self):
        self.db={}
        self.dumpdb()
        return True

Here’s the function to reset the database, resetdb! It’s so simple: first, what we do is re-assign our in-memory database with an empty JSON object and it just saves it! And that’s it! Our Database is now again clean shaven.

Finally… 🎉

That’s it friends! We have created our own Toy Database ! 🎉🎉 Actually, FoobarDB is just a simple demo of a database. It’s like a cheap DIY toy: you can improve it any way you want. You can also add many other functions according to your needs.

Full Source is Here 👉 bauripalash/foobardb

I hope, you enjoyed it! Let me know your suggestions, ideas or mistakes I’ve made in the comments below! 👇

Thank you! See you soon!

Python GUI Programming Projects using Tkinter and Python 3

Python GUI Programming Projects using Tkinter and Python 3

Python GUI Programming Projects using Tkinter and Python 3

Description
Learn Hands-On Python Programming By Creating Projects, GUIs and Graphics

Python is a dynamic modern object -oriented programming language
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Python is what is referred to as a high level language
Python is used in the industry for things like embedded software, web development, desktop applications, and even mobile apps!
SQL-Lite allows your applications to become even more powerful by storing, retrieving, and filtering through large data sets easily
If you want to learn to code, Python GUIs are the best way to start!

I designed this programming course to be easily understood by absolute beginners and young people. We start with basic Python programming concepts. Reinforce the same by developing Project and GUIs.

Why Python?

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When and how do I start a career as a Python programmer?

In an independent third party survey, it has been revealed that the Python programming language is currently the most popular language for data scientists worldwide. This claim is substantiated by the Institute of Electrical and Electronic Engineers, which tracks programming languages by popularity. According to them, Python is the second most popular programming language this year for development on the web after Java.

Python Job Profiles
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The median total pay for Python jobs in California, United States is $74,410, for a professional with one year of experience
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The first chart depicts average salary for a Python professional with one year of experience and the second chart depicts the average salaries by years of experience
Who Uses Python?

This course gives you a solid set of skills in one of today’s top programming languages. Today’s biggest companies (and smartest startups) use Python, including Google, Facebook, Instagram, Amazon, IBM, and NASA. Python is increasingly being used for scientific computations and data analysis
Take this course today and learn the skills you need to rub shoulders with today’s tech industry giants. Have fun, create and control intriguing and interactive Python GUIs, and enjoy a bright future! Best of Luck
Who is the target audience?

Anyone who wants to learn to code
For Complete Programming Beginners
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This course was designed for students with little to no programming experience
People interested in building Projects
Anyone looking to start with Python GUI development
Basic knowledge
Access to a computer
Download Python (FREE)
Should have an interest in programming
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Install Python 3.6 on your computer
What will you learn
Build Python Graphical User Interfaces(GUI) with Tkinter
Be able to use the in-built Python modules for their own projects
Use programming fundamentals to build a calculator
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Build Your GUI in Python programming
Use programming fundamentals to build a Project
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Quizzes
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Guide to Python Programming Language

Guide to Python Programming Language

Guide to Python Programming Language

Description
The course will lead you from beginning level to advance in Python Programming Language. You do not need any prior knowledge on Python or any programming language or even programming to join the course and become an expert on the topic.

The course is begin continuously developing by adding lectures regularly.

Please see the Promo and free sample video to get to know more.

Hope you will enjoy it.

Basic knowledge
An Enthusiast Mind
A Computer
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Internet Connection
What will you learn
Will Be Expert On Python Programming Language
Build Application On Python Programming Language

Python Connect MySQL Database

Python Connect MySQL Database

Databases are critical for storing and processing data even if you consider a powerful programming language like Python. Ever wondered where does this whole large set of data is stored in or fetched from?

Databases are critical for storing and processing data even if you consider a powerful programming language like Python. Ever wondered where does this whole large set of data is stored in or fetched from?

In this article, I’ll talk about the same and take you through the following aspects in detail.

  •        What is a [database](https://morioh.com/topic/database "database")?
    
  •        What is [MySQLdb](https://morioh.com/topic/mysql "MySQLdb")?
    
  •        How does [Python](https://morioh.com/topic/python "Python") connect to a database?
    
  •        Creating a Database
    
  •        Database Operations-[CRUD](https://morioh.com/p/60b941830c01 "CRUD")
    

Let’s get started :)

What is a database?

A database is basically a collection of structured data in such a way that it can easily be retrieved, managed and accessed in various ways. One of the simplest forms of databases is a text database. Relational databases are the most popular database system which includes the following:

Among all these databases, MySQL is one of the easiest databases to work with. Let me walk you through about this in detail.

What is MySQLdb?

MySQLdb is an open-source freely available relational database management system that uses Structured Query Language. Now one of the most important question here is “What is SQL?”

SQL (Structured Query Language) is a standard language for relational databases that allow users to do various operations on data like, Manipulating, Creating, Dropping, etc. In a nutshell, SQL allows you to do anything with the data.

Let’s move ahead and dive deep into Python database connection wherein you will learn how to connect with the database.

**How does Python connect to a database? **

It is very simple to connect Python with the database. Refer the below image which illustrates a Python connection with the database where how a connection request is sent to MySQL connector Python, gets accepted from the database and cursor is executed with result data.

Before connecting to the MySQL database, make sure you have MySQL installer installed on your computer. It provides a comprehensive set of tools which helps in installing MySQL with the following components:
MySQL server All available connectorsMySQL WorkbenchMySQL NotifierTools for Excel and Microsoft Visual StudioMySQL Sample DatabasesMySQL Documentation
To download the MySQL installer please go through the following video which talks about the various steps that you need to follow while installing MySQL.

Before proceeding you should make sure you have MySQL db installed on your computer. Refer the below commands for installing MySQL in command prompt and pycharm:

Using Pip:

Command:

pip install mysql-connector

**Using Pycharm **

Command:

import mysql.connector

Output:

C:UsersHarshit_KantPycharmProjectstest1venvScriptspython.exe C:/Users/Harshit_Kant/PycharmProjects/test1/venv/python-db-conn.py

Process finished with exit code 0

Moving on in this article with Python Database Connection let us see the parameters required to connect to the database:

  • **Username- It is simply the username you give to work MySQL server with, the Default username is root.
  • **Password- **Password is given by the user when you have installed the MySQL database. I am giving password here as ‘password123’
  • Host Name- This basically is the server name or IP address on which your MySQL is running, If it is a ‘localhost’, then your IP address is 127.0.0.0

I will show you from a coding perspective to connect python with MySQL database.

Example:

import mysql.connector
 
mydb=mysql.connector.connect(host="localhost",user="root",passwd="password123") // I have used 'host','username','password'
 
print(mydb)

Output:

C:UsersHarshit_KantPycharmProjectstest1venvScriptspython.exe C:/Users/Harshit_Kant/PycharmProjects/test1/venv/python-db-conn.py

<mysql.connector.connection_cext.CMySQLConnection object at 0x000001606D7BD6A0>

Process finished with exit code 0

**Explanation: **Here ‘mydb’ is just an instance. From the output, you can clearly see that it has connected to the database.

Next up in Python Database Connection, you will learn how to create a database.

Creating a Database:

Once the database connection is established, you are ready to create your own database which will be acting as a bridge between your python and MySQL server.

Let’s see the implementation part of it.

Example:

import mysql.connector
 
mydb=mysql.connector.connect(host="localhost",user="root",passwd="password123")
mycursor=mydb.cursor()
mycursor.execute("create database harshdb")

Output:

C:/Users/Harshit_Kant/PycharmProjects/test1/venv/python-db-conn.py

Process finished with exit code 0

Explanation:

  • In the above program, I have made use of cursor which is basically an object that is used to communicate to your entire MySQL server through which I am able to create my own database.
  • You can see from the output that my database with the name”harshdb” is created which is custom, as you can give any name to your database.

If you want to see the databases in your MySQL server, you can implement the following piece of code in pycharm:

Example :

import mysql.connector
 
mydb=mysql.connector.connect(host="localhost",user="root",passwd="password123")
mycursor=mydb.cursor()
mycursor.execute("show databases")
 
for db in mycursor:
print(db)

Output:

C:UsersHarshit_KantPycharmProjectstest1venvScriptspython.exe C:/Users/Harshit_Kant/PycharmProjects/test1/venv/python-db-conn.py

(‘harshdb’,)

(‘information_schema’,)

(‘mysql’,)

(‘performance_schema’,)

(‘sakila’,)

(‘sys’,)

(‘world’,)

Process finished with exit code 0

Explanation:

  • By implementing the above-written code I have tried showing all the databases which are existing in MySQL server.

Now that you have created your database, let’s dive deep into one of the most important aspects of Python Database Connection by doing few operations in it. Let us understand this in detail.

Database Operations[CRUD]:

There are numerous operations a programmer can perform using databases and SQL in order to have sound knowledge of database programming and MySQL.

I have demonstrated the CRUD operations below

  • Create– It is an SQL statement used to create a record in the table or can say it is used for creating a table.
  • **Read- **It is used for fetching useful information from the database.
  • **Update- **This particular SQL statement is used for updating the records in the table or updating the table.
  • **Delete- **As the name itself justifies this command is used for deleting the table.

Let us look at each aspect in detail from the coding perspective.

Create Operation:

import mysql.connector
 
mydb=mysql.connector.connect(host="localhost",user="root",passwd="password123",database=harshdb)
 
mycursor=mydb.cursor()
 
mycursor.execute("create table employee(name varchar(250),sal int(20))")

Output:

C:UsersHarshit_KantPycharmProjectstest1venvScriptspython.exe C:/Users/Harshit_Kant/PycharmProjects/test1/venv/python-db-conn.py

Process finished with exit code 0

Explanation:

  • In the above-given program, I have created a table ’employee’.
  • Table employee has two fields ‘name’ and ‘sal’.
  • Here, the User id is “root” and Password is “password123” used for accessing harshdb.

Below given Screenshot shows the table ’employee’ and returns the fields ‘name’ and ‘sal’.

In order to see the table which I have created, refer to the following code in python

import mysql.connector
 
mydb=mysql.connector.connect(host="localhost",user="root",passwd="password123",database="harshdb")
mycursor=mydb.cursor()
mycursor.execute("show tables")
 
for tb in mycursor:
    print(tb)

Output:

C:UsersHarshit_KantPycharmProjectstest1venvScriptspython.exe C:/Users/Harshit_Kant/PycharmProjects/test1/venv/python-db-conn.py

(’employee’,)

Process finished with exit code 0

Below given Screenshot shows the table ’employee’ which I have created.

Screenshot:

Now that you have seen how a table is created, let us look at how a user can fetch values from it.

Read Operation:

This particular operation happens in various stages. In order to do that first stage is to populate the table.

Code:

import mysql.connector
 
mydb=mysql.connector.connect(host="localhost",user="root",passwd="password123",database="harshdb")
mycursor=mydb.cursor()
 
sqlformula = "Insert into employee(name,sal) values(%s,%s)"//'values has placeholders
 
employees = [("harshit",200000),("rahul", 30000),("avinash", 40000),("amit", 50000),]//Created an array of emplpoyees
 
 
mycursor.executemany(sqlformula, employees)//Passing the data
 
mydb.commit()//SQL statement used for saving the changes

Output:

C:UsersHarshit_KantPycharmProjectstest1venvScriptspython.exe C:/Users/Harshit_Kant/PycharmProjects/test1/venv/python-db-conn.py

Process finished with exit code 0

In the above code, I have populated the data by using an array of employees by writing SQL statements in Python. Below a screenshot of the database will show the changes

Here,’harshit’ is used two times in the record while created the array.

**Stage 2: **In this stage, we will make use of the “select” SQL statement where the actual read operation will take place.

  • fetchall()– This particular function fetches all the data from the last executed statement.
  • **fetchone()- **This particular statement fetches one data from the last executed statement.

Code:

import mysql.connector
 
mydb=mysql.connector.connect(host="localhost",user="root",passwd="password123",database="harshdb")
mycursor=mydb.cursor()
 
mycursor.execute("select * from employee")
 
myresult = mycursor.fetchall()
 
for row in myresult:
    print(row)

Output:

(‘harshit’, 200000)

(‘harshit’, 200000)

(‘rahul’, 30000)

(‘avinash’, 40000)

(‘amit’, 50000)

Process finished with exit code 0

**Explanation: **In the above code we have made use of the function ‘fetchall()’. It fetches all the data from the last executed statement.

Given below is the screenshot of the database.

Code:

import mysql.connector
 
mydb=mysql.connector.connect(host="localhost",user="root",passwd="password123",database="harshdb")
mycursor=mydb.cursor()
 
mycursor.execute("select name from employee")//selecting the field i want data to be fetched from
 
myresult = mycursor.fetchone()
 
for row in myresult:
    print(row)

Output:

C:UsersHarshit_KantPycharmProjectstest1venvScriptspython.exe C:/Users/Harshit_Kant/PycharmProjects/test1/venv/python-db-conn.py

harshit

Process finished with exit code 0

**Explanation: **In the above code, I have made use of the function “fetchone()” which basically fetches a single data from the last executed statement.

That was all about ‘Read operation’, let’s dive deep into Update operation.

Update Operation:

This SQL statement is used for updating the records in the table. Let’s implement the code and see how the changes are taking place.

Code:

import mysql.connector
 
mydb=mysql.connector.connect(host="localhost",user="root",passwd="password123",database="harshdb")
mycursor=mydb.cursor()
 
sql = "Update employee SET sal = 70000 WHERE name = 'harshit'"
 
mycursor.execute(sql)
 
mydb.commit()

Output:

C:UsersHarshit_KantPycharmProjectstest1venvScriptspython.exe C:/Users/Harshit_Kant/PycharmProjects/test1/venv/python-db-conn.py

Process finished with exit code 0

**Explanation: **We have updated the row “sal” of record harshit in the above-given code. Below given Screenshot will give you a clear picture.

Screenshot:

As you can clearly see row ‘sal’ of record ‘harshit’ is updated to 70000.

This was all about Update operation, moving on with “Python Connect MySQL Database” article we will see the last operation which is ‘delete’.

Delete Operation:

As the name itself justifies, Delete operation is used for the deletion of records from the table. Let’s understand it from a coding perspective.

Code:

import mysql.connector
 
mydb=mysql.connector.connect(host="localhost",user="root",passwd="password123",database="harshdb")
mycursor=mydb.cursor()
 
sql = "DELETE FROM employee  WHERE name = 'harshit'"
 
mycursor.execute(sql)
 
mydb.commit()

Output:

C:UsersHarshit_KantPycharmProjectstest1venvScriptspython.exe C:/Users/Harshit_Kant/PycharmProjects/test1/venv/python-db-conn.py

Process finished with exit code 0

**Explanation: **In the above code I have deleted a record ‘harshit’ as it was repeated twice.

Below given screenshot will give you a better picture.

As you can clearly see from the screenshot record ‘harshit’ has been deleted. Well, you can do another set of manipulation from the delete operation itself like deleting salary. I had mentioned only two fields so the operations on the record which I could do is limited, but you can create more fields under the same table ’employee’ or any other table you create.

This brings us to the end of our article on “Python Connect MySQL Database”. I hope you are clear with all the concepts related to database, MYSQL db, database operations in python. Make sure you practice as much as possible and revert your experience.