Month: July 2021

sqlite3 module provides nice ways to deal with Sqlite database. We will cover a way to create a table and pump data into the table with a right way.

I’d recommend this nice tool called DB Browser for SQLite. This tool is very useful when you browse the data in the database and execute SQL scripts.

First, let’s create a sample table.

    def create_table_hoge(self, conn):
        cur = conn.cursor()
        cur.execute('''CREATE TABLE HOGE (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        col1 text,
        col2 VARCHAR(10)
        )''')

We will pump bunch of dummy data into the table using the following code.

conn = sqlite3.connect(self.db_name)
        cur = conn.cursor()
        for i in range(1000):
            cur.execute('''INSERT INTO HOGE (col1, col2)
            VALUES (?, ?);
            ''', (f"test{i}",f"test{i+1}"))
            conn.commit()
            print(cur.lastrowid)

Note that cursor.execute method takes SQL statement and the parameter values as tuple. You can see the values are being accepted with question marks and actual values are in the tuple. I haven’t tried it but it probably prevents SQL injection rather than using a straight SQL like INSERT INTO HOGE (col1, col2) VALUES (‘test1’, ‘test2’).

When I browse HOGE table with DB Browser for SQLite, it looks like the following.

There may be times when you want to dynamically execute functions in Python.

If you want to execute function depending on conditions, you’d normally write the following code.

import unittest
class test01(unittest.TestCase):
    def test_helloworld(self):
        function_to_execute = 'foo'
        if function_to_execute == 'foo':
            test01.foo()
        elif function_to_execute == 'bar':
            test01.bar()

    def foo():
        print('hello from foo')

    def bar():
        print('hello from bar')

Writing code like that easily gets unmanageable when there are many conditions. It’s better to dynamically call functions.

import unittest

class test01(unittest.TestCase):
    def test_helloworld(self):
        function_to_execute = 'foo'
        func = getattr(test01, function_to_execute)
        func()

    def foo():
        print('hello from foo')

    def bar():
        print('hello from bar')

You might have quite a bit of functions to manage, the calling method would not be so bad by dynamically calling functions.