![Open a connection to MySQL
Database
T
o create connection, connect( ) function is used
Its syntax is:
connect(host=<server_name>,user=<user_name>,
passwd=<password>[,database=<database>])
Here server_name means database servername, generally
it is given as “localhost”
User_name means user by which we connect with mysql
generally it is given as “root”
Password is the password of user “root”
Database is the name of database whose data(table) we
want to use.](https://image.slidesharecdn.com/5-241225040346-bf470b64/85/SQL-Connectivity-python-for-beginners-easy-explanation-with-concepts-and-output-pptx-7-320.jpg)
SQL-Connectivity python for beginners easy explanation with concepts and output .pptx
- 1. INTERF ACE PYTHON WITH MYSQL Connecting Python application with
- 3. Introductio n Every application required data to be stored for future reference to manipulate data. Today every application stores data in database for this purpose. For example, reservation system stores passengers details for reserving the seats and later on for sending some messages or for printing tickets etc. In school student details are saved for many reasons like attendance, fee collections, exams, report card etc. Python allows us to connect all types of database like Oracle, SQLServer, MySQL . In our syllabus we have to understand how to connect Python programs with MySQL
- 4. Pre-requisite to connect Python with MySQL Before we connect python program with any database like MySQL we need to build a bridge to connect Python and MySQL. T o build this bridge so that data can travel both ways we need a connector called “mysql.connector”. We can install “mysql.connector” by using following methods: At command prompt (Administrator login) Type “pip install mysql.connector” and press enter (internet connection is required) This connector will work only for MySQL 5.7.3 or later Or open “https://dev.mysql.com/downloads/connector/python/” anddownloadconnectorasper OS and Python version.
- 5. Connecting to MySQL from Python Once the connector is installed you are ready to connect your python program to MySQL. The following steps to follow while connecting your python program with MySQL Open python Import the package required (import mysql.connector) Open the connection to database Create a cursor instance Execute the query and store it in resultset Extract data from resultset Clean up the environment
- 6. Importing mysql.connector import mysql.connector Or import mysql.connector as ms Here “ms” is an alias, so every time we can use “ms” in place of “mysql.connector”
- 7. Open a connection to MySQL Database T o create connection, connect( ) function is used Its syntax is: connect(host=<server_name>,user=<user_name>, passwd=<password>[,database=<database>]) Here server_name means database servername, generally it is given as “localhost” User_name means user by which we connect with mysql generally it is given as “root” Password is the password of user “root” Database is the name of database whose data(table) we want to use.
- 8. Example: To establish connection with MySQL is_connected() function returns true if connection is established otherwise false “mys” is an alias of package “mysql.connector” “mycon” is connection object which storesconnection established with MySQL
- 10. Creating Cursor It is a useful control structure of database connectivity. When we fire a query to database, it is executed and resultset (set of records) is sent over the connection in one go. We may want to access data one row at a time, but query processing cannot happens as one row at a time, so cursor help usin performing this task. Cursor stores all the data as a temporary container of returned data and we can fetch data one row at a time from Cursor.
- 11. Creating Cursor and Executing Query TO CREATE CURSOR We use cursor() function to create a cursor Cursor_name = connectionObject.cursor( ) For e.g. mycursor = mycon.cursor() TO EXECUTE QUERY We use execute( ) function to send query to connection Cursor_name.execute(query) For e.g. mycursor.execute(“select * from emp ) ‟
- 12. Example - Cursor Output shows cursor is created and query is fired and stored, but no data is coming. T o fetch data we have to use functions like fetchall( ), fetchone( ), fetchmany( ) are used.
- 13. mysql.connector as mys Mysql connector mys
- 15. Fetchall( ) – method extracts all rows
- 18. Inserting data in MySQL table from Python INSERT and UPDATE operation are executed in the same way we execute SELECT query using execute( ) but one thing to remember, after executing DML Commands -insert or update or delete query we must commit our query using connection object with commit( ). For e.g. (if our connection object nameis mycon) mycon.commit( )
- 19. Example : inserting data BEFORE PROGRAM EXECUTION AFTER PROGRAM EXECUTION
- 21. Fetching(extracting) data from ResultSet T o extract data from cursor following functions are used: fetchall( ) : it will return all the record in the form of tuple. fetchone( ) : it return one record from the result set. i.e. first time it will return first record, next time it will return second record and so on. If no more record it will return None. fetchmany(n) : it will return n number of records. It no more record it will return an empty tuple. rowcount: it will return number of rows retrieved from the cursor so far.
- 27. Guess the output
- 29. Parameterized Query We can pass values to query to perform dynamic search like we want to search for any employee number entered during runtime or to search any other column values. T o Create Parameterized query we can use various methods like: Concatenating dynamic variable to query values are entered. String template with % formatting String template with { } and format function in which
- 31. String template with %s formatting In this method we will use %s in place of values to substitute and then pass the value for that place.
- 32. String template with %s formatting
- 33. String template with { } and format( ) In this method in place of % s we will use { } and to pass values for these placeholder format( ) is used. Inside we can optionally give 0,1,2… values for e.g. {0},{1} but its not mandatory. we can also optionally pass named parameter inside { } sothat while passing we need to pass. not to For e.g. values through format function remember the order of value {roll},{name} etc.
- 34. String template with { } and format( )
- 35. String template with { } and format()
- 36. UPDATING RECORDS
- 38. DELETING RECORDS