SQLite - Python

In this chapter, you will learn how to use SQLite in Python programs.

Installation

SQLite3 can be integrated with Python using sqpte3 module, which was written by Gerhard Haring. It provides an SQL interface comppant with the DB-API 2.0 specification described by PEP 249. You do not need to install this module separately because it is shipped by default along with Python version 2.5.x onwards.

To use sqpte3 module, you must first create a connection object that represents the database and then optionally you can create a cursor object, which will help you in executing all the SQL statements.

Python sqpte3 module APIs

Following are important sqpte3 module routines, which can suffice your requirement to work with SQLite database from your Python program. If you are looking for a more sophisticated apppcation, then you can look into Python sqpte3 module s official documentation.

Connect To Database

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.

#!/usr/bin/python

import sqpte3

conn = sqpte3.connect( test.db )

print "Opened database successfully";

Here, you can also supply database name as the special name :memory: to create a database in RAM. Now, let s run the above program to create our database test.db in the current directory. You can change your path as per your requirement. Keep the above code in sqpte.py file and execute it as shown below. If the database is successfully created, then it will display the following message.

$chmod +x sqpte.py
$./sqpte.py
Open database successfully

Create a Table

Following Python program will be used to create a table in the previously created database.

#!/usr/bin/python

import sqpte3

conn = sqpte3.connect( test.db )
print "Opened database successfully";

conn.execute(   CREATE TABLE COMPANY
         (ID INT PRIMARY KEY     NOT NULL,
         NAME           TEXT    NOT NULL,
         AGE            INT     NOT NULL,
         ADDRESS        CHAR(50),
         SALARY         REAL);   )
print "Table created successfully";

conn.close()

When the above program is executed, it will create the COMPANY table in your test.db and it will display the following messages −

Opened database successfully
Table created successfully

INSERT Operation

Following Python program shows how to create records in the COMPANY table created in the above example.

#!/usr/bin/python

import sqpte3

conn = sqpte3.connect( test.db )
print "Opened database successfully";

conn.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) 
      VALUES (1,  Paul , 32,  Capfornia , 20000.00 )");

conn.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) 
      VALUES (2,  Allen , 25,  Texas , 15000.00 )");

conn.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) 
      VALUES (3,  Teddy , 23,  Norway , 20000.00 )");

conn.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) 
      VALUES (4,  Mark , 25,  Rich-Mond  , 65000.00 )");

conn.commit()
print "Records created successfully";
conn.close()

When the above program is executed, it will create the given records in the COMPANY table and it will display the following two pnes −

Opened database successfully
Records created successfully

SELECT Operation

Following Python program shows how to fetch and display records from the COMPANY table created in the above example.

#!/usr/bin/python

import sqpte3

conn = sqpte3.connect( test.db )
print "Opened database successfully";

cursor = conn.execute("SELECT id, name, address, salary from COMPANY")
for row in cursor:
   print "ID = ", row[0]
   print "NAME = ", row[1]
   print "ADDRESS = ", row[2]
   print "SALARY = ", row[3], "
"

print "Operation done successfully";
conn.close()

When the above program is executed, it will produce the following result.

Opened database successfully
ID = 1
NAME = Paul
ADDRESS = Capfornia
SALARY = 20000.0

ID = 2
NAME = Allen
ADDRESS = Texas
SALARY = 15000.0

ID = 3
NAME = Teddy
ADDRESS = Norway
SALARY = 20000.0

ID = 4
NAME = Mark
ADDRESS = Rich-Mond
SALARY = 65000.0

Operation done successfully

UPDATE Operation

Following Python code shows how to use UPDATE statement to update any record and then fetch and display the updated records from the COMPANY table.

#!/usr/bin/python

import sqpte3

conn = sqpte3.connect( test.db )
print "Opened database successfully";

conn.execute("UPDATE COMPANY set SALARY = 25000.00 where ID = 1")
conn.commit()
print "Total number of rows updated :", conn.total_changes

cursor = conn.execute("SELECT id, name, address, salary from COMPANY")
for row in cursor:
   print "ID = ", row[0]
   print "NAME = ", row[1]
   print "ADDRESS = ", row[2]
   print "SALARY = ", row[3], "
"

print "Operation done successfully";
conn.close()

When the above program is executed, it will produce the following result.

Opened database successfully
Total number of rows updated : 1
ID = 1
NAME = Paul
ADDRESS = Capfornia
SALARY = 25000.0

ID = 2
NAME = Allen
ADDRESS = Texas
SALARY = 15000.0

ID = 3
NAME = Teddy
ADDRESS = Norway
SALARY = 20000.0

ID = 4
NAME = Mark
ADDRESS = Rich-Mond
SALARY = 65000.0

Operation done successfully

DELETE Operation

Following Python code shows how to use DELETE statement to delete any record and then fetch and display the remaining records from the COMPANY table.

#!/usr/bin/python

import sqpte3

conn = sqpte3.connect( test.db )
print "Opened database successfully";

conn.execute("DELETE from COMPANY where ID = 2;")
conn.commit()
print "Total number of rows deleted :", conn.total_changes

cursor = conn.execute("SELECT id, name, address, salary from COMPANY")
for row in cursor:
   print "ID = ", row[0]
   print "NAME = ", row[1]
   print "ADDRESS = ", row[2]
   print "SALARY = ", row[3], "
"

print "Operation done successfully";
conn.close()

When the above program is executed, it will produce the following result.

Opened database successfully
Total number of rows deleted : 1
ID = 1
NAME = Paul
ADDRESS = Capfornia
SALARY = 20000.0

ID = 3
NAME = Teddy
ADDRESS = Norway
SALARY = 20000.0

ID = 4
NAME = Mark
ADDRESS = Rich-Mond
SALARY = 65000.0

Operation done successfully