connecting python with mysql

1. INTERF
ACEPYTHONWITH
MYSQL
ConnectingPythonapplication with MySQL

2. Introduction
 Every application required data to be stored for future
reference to manipulate data. Today every application
storesdata in database for this purpose
 For example, reservation system stores passengers
details for reserving the seats and later on for sending
somemessagesor for printing tickets etc.
 Python allows us to connect all types of database like
Oracle, SQLServer, MySQL.

3. Pre-requisite to connectPythonwith
MySQL
 Before we connect python program with any database
like MySQL we need to build a bridge to connect
PythonandMySQL.
 T
obuild thisbridge sothat data cantravel both ways we
need a connectorcalled “mysql.connector”.
 We can install “mysql.connector” by using following
methods:
At commandprompt (Administrator login)
 Type“pip install mysql.connector”and press enter
 (internet connectionin required)
 Thisconnector will work only for MySQL5.7.3 orlater
Or open
“https://dev.mysql.com/downloads/connector/python/”

4. Connectingto MySQLfrom Python
 Oncethe connectorisinstalled youare ready to
connectyour python program to MySQL.
 Thefollowing stepsto follow while connectingyour
python program with MySQL
Open python
Import the package required (import mysql.connector)
Open the connectionto database
Create a cursor instance
Executethe query and store it in resultset
Extract data from resultset
Clean up the environment

5. Importing mysql.connector
import mysql.connector
Or
import mysql.connectoras ms
Here“ms”isan alias, soevery time wecanuse“ms”in
place of “mysql.connector”

6. Open a connection toMySQL Database
 T
ocreate connection,connect()function isused
 Itssyntaxis:
connect(host=<server_name>,user=<user_name>,
passwd=<password>[,database=<database>])
 Here server_namemeansdatabase servername, generally
it isgiven as“localhost”
 User_namemeansuserby whichwe connectwith mysql
generally it isgiven as “root”
 Passwdisthe password of user“root”
 Database isthe nameof database whosedata(table) we
want to use

7. Example: Toestablish connection with MySQL
is_connected() function returns
true if connection isestablished
otherwise false
“mys” isan alias of package “mysql.connector”

8. Creating Cursor
 It isa usefulcontrol structure of database connectivity.
 When we fire a query to database, it is executed and
resultset (set of records) is sent over theconnectionin one
go.
 We may want to access data one row at a time, but
query processing cannot happens as one row at a time,
socursor help usin performing this task. Cursor stores all
the data as a temporary container of returned data
and wecanfetch data onerow at a time from Cursor.

9. Creating Cursor and Executing Query
 TO CREATE CURSOR
Cursor_name= connectionObject.cursor()
For e.g.
mycursor= mycon.cursor()
 TO EXECUTE QUERY
 We useexecute()function to sendquery to connection
 Cursor_name.execute(query)
 For e.g.
 mycursor.execute("select* from emp")

10. 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

11. Fetching(extracting) data from ResultSet
 T
oextract data from cursorfollowing functionsare used:
fetchall() :it will return all the record in the form of listof
tuples.
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
morerecord it will return an empty list.
rowcount : it will return number of rows retrieved from
the cursorsofar.

12. Table to work (emp)

13. Example– fetchall()

14. Example4: fetchone()

15. Example5: fetchmany(n)

16. 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
valuesare entered.
String template with % formatting
String template with {} and format function
in which

17. Concatenating variable with query

18. String template with %sformatting
 Inthismethodwewill use%sin place of valuesto
substituteand thenpassthe value for that place.

19. String template with %sformatting

20. String templatewith {} and format()
 Inthis method in place of %swe will use{} and to pass
valuesfor theseplaceholder format() isused. Insidewe
canoptionally give 0,1,2… valuesfor e.g.
{0},{1} but its not mandatory. we can also optionally
passnamedparameter inside {} sothat whilepassing
we need
to pass.
of
value
not to
For e.g.
values through format function
remember the order
{roll},{name} etc.

21. String templatewith {} and format()

22. String templatewith {} and format()

24. Inserting data in MySQL table from Python
 INSERT, UPDATE AND DELETE operation are
executed in the same way we execute SELECTquery
using execute() but one thing to remember, after
executing insert or update query we must commit
our query using connectionobjectwith commit().
 Fore.g. (if our connectionobject nameis mycon)
 mycon.commit()

25. Example: inserting data
BEFORE PROGRAM EXECUTION
AFTER PROGRAM EXECUTION

26. Example: Updating record