How to Alter a SQLite Table using Python ?

In this article, we will discuss how can we alter tables in the SQLite database from a Python program using the sqlite3 module. 

We can do this by using ALTER statement. It allows to:

• Add one or more column to the table

Change the name of the table.

Adding a column to a table

The syntax of ALTER TABLE to add a new column in an existing table in SQLite is given below:

ALTER TABLE table_name ADD COLUMN column_name colume_type

The column is added but will have all the values to be NULL.

To create a table:

Python3

import sqlite3

# Connecting to sqlite
connection_obj = sqlite3.connect('geek.db')

# cursor object
cursor_obj = connection_obj.cursor()

# Drop the GEEK table if already exists.
cursor_obj.execute("DROP TABLE IF EXISTS GEEK")

# Creating table
table = """ CREATE TABLE GEEK (
            Email VARCHAR(255) NOT NULL,
            Name CHAR(25) NOT NULL,
            Score INT
        ); """

cursor_obj.execute(table)

# Inserting data into geek table
connection_obj.execute(
    """INSERT INTO GEEK (Email,Name,Score) VALUES ("geekk1@gmail.com","Geek1",25)""")
connection_obj.execute(
    """INSERT INTO GEEK (Email,Name,Score) VALUES ("geekk2@gmail.com","Geek2",15)""")
connection_obj.execute(
    """INSERT INTO GEEK (Email,Name,Score) VALUES ("geekk3@gmail.com","Geek3",36)""")
connection_obj.execute(
    """INSERT INTO GEEK (Email,Name,Score) VALUES ("geekk4@gmail.com","Geek4",27)""")
connection_obj.execute(
    """INSERT INTO GEEK (Email,Name,Score) VALUES ("geekk5@gmail.com","Geek5",40)""")
connection_obj.execute(
    """INSERT INTO GEEK (Email,Name,Score) VALUES ("geekk6@gmail.com","Geek6",14)""")
connection_obj.execute(
    """INSERT INTO GEEK (Email,Name,Score) VALUES ("geekk7@gmail.com","Geek7",10)""")

# Display table
data = cursor_obj.execute("""SELECT * FROM GEEK""")
print('GEEK Table:')
for row in data:
    print(row)

connection_obj.commit()

# Close the connection
connection_obj.close()

Output:

Now we add a new column “UserName”:

Python3

import sqlite3

# Connecting to sqlite
connection_obj = sqlite3.connect('geek.db')

# cursor object
cursor_obj = connection_obj.cursor()

# Add a new column to geek table
new_column = "ALTER TABLE GEEK ADD COLUMN UserName CHAR(25)"

cursor_obj.execute(new_column)

# Display table
data = cursor_obj.execute("SELECT * FROM GEEK")
print('GEEK Table:')
for row in data:
    print(row)

connection_obj.commit()

# Close the connection
connection_obj.close()

Output:

Changing the name of the table

The syntax of ALTER TABLE to change the name of the table in SQLite is given below:

ALTER TABLE table_name RENAME TO newTableName;

We will use the same GEEK table that we created above:

Python3

import sqlite3

# Connecting to sqlite
connection_obj = sqlite3.connect('geek.db')

# cursor object
cursor_obj = connection_obj.cursor()

# select from sqlite_master
cursor_obj.execute("SELECT * FROM sqlite_master")

table = cursor_obj.fetchall()
print("Before changing the name of Table")
print("The name of the table:", table[0][2])

# Rename the SQLite Table
renameTable = "ALTER TABLE GEEK RENAME TO GFG"
cursor_obj.execute(renameTable)


# select from sqlite_master
cursor_obj.execute("SELECT * FROM sqlite_master")

table = cursor_obj.fetchall()

print("After changing the name of Table")
print("The name of the table:", table[0][2])

connection_obj.commit()

connection_obj.close()

Output: