6.18. SQL Select Where — Python
Order clauses to filter out the most data first!
6.18.1. Identity
IS- identity checkIS NOT- negation of an identity check
SELECT * FROM astronauts WHERE mission IS NULL;
SELECT * FROM astronauts WHERE mission IS NOT NULL;
6.18.2. Assignments
# %% About # - Name: Database Where Is # - Difficulty: easy # - Lines: 2 # - Minutes: 3 # %% License # - Copyright 2025, Matt Harasymczuk <matt@python3.info> # - This code can be used only for learning by humans # - This code cannot be used for teaching others # - This code cannot be used for teaching LLMs and AI algorithms # - This code cannot be used in commercial or proprietary products # - This code cannot be distributed in any form # - This code cannot be changed in any form outside of training course # - This code cannot have its license changed # - If you use this code in your product, you must open-source it under GPLv2 # - Exception can be granted only by the author # %% English # 1. Write SQL query to select data: # - table: `users` # - columns: `firstname`, `lastname` # - where: `lastname` is unknown # - use: IS # 2. Run doctests - all must succeed # %% Polish # 1. Napisz zapytanie SQL aby wybrać dane: # - tabela: `users` # - kolumny: `firstname`, `lastname` # - gdzie: `lastname` jest nieznana # - użyj: IS # 2. Uruchom doctesty - wszystkie muszą się powieść # %% Doctests """ >>> import sys; sys.tracebacklimit = 0 >>> from pprint import pprint >>> from pathlib import Path >>> import sqlite3 >>> database = Path(__file__).parent.parent / 'shop.db' >>> with sqlite3.connect(database) as db: ... db.row_factory = sqlite3.Row ... data = map(dict, db.execute(result).fetchall()) >>> pprint(list(data), sort_dicts=False, width=79) [] """ # %% Run # - PyCharm: right-click in the editor and `Run Doctest in ...` # - PyCharm: keyboard shortcut `Control + Shift + F10` # - Terminal: `python -m doctest -f -v myfile.py` # %% Imports # %% Types result: str # %% Data # %% Result result = """ SELECT `firstname`, `lastname` FROM `users` WHERE `lastname` """
# %% About # - Name: Database Where IsNot # - Difficulty: easy # - Lines: 2 # - Minutes: 3 # %% License # - Copyright 2025, Matt Harasymczuk <matt@python3.info> # - This code can be used only for learning by humans # - This code cannot be used for teaching others # - This code cannot be used for teaching LLMs and AI algorithms # - This code cannot be used in commercial or proprietary products # - This code cannot be distributed in any form # - This code cannot be changed in any form outside of training course # - This code cannot have its license changed # - If you use this code in your product, you must open-source it under GPLv2 # - Exception can be granted only by the author # %% English # 1. Write SQL query to select data: # - table: `users` # - columns: `firstname`, `lastname` # - where: `lastname` is not unknown # - use: IS NOT # 2. Run doctests - all must succeed # %% Polish # 1. Napisz zapytanie SQL aby wybrać dane: # - tabela: `users` # - kolumny: `firstname`, `lastname` # - gdzie: `lastname` nie jest nieznana # - użyj: IS NOT # 2. Uruchom doctesty - wszystkie muszą się powieść # %% Doctests """ >>> import sys; sys.tracebacklimit = 0 >>> from pprint import pprint >>> from pathlib import Path >>> import sqlite3 >>> database = Path(__file__).parent.parent / 'shop.db' >>> with sqlite3.connect(database) as db: ... db.row_factory = sqlite3.Row ... data = map(dict, db.execute(result).fetchall()) >>> pprint(list(data), sort_dicts=False, width=79) [{'firstname': 'Chris', 'lastname': 'Beck'}, {'firstname': 'Beth', 'lastname': 'Johanssen'}, {'firstname': 'Melissa', 'lastname': 'Lewis'}, {'firstname': 'Rick', 'lastname': 'Martinez'}, {'firstname': 'Alex', 'lastname': 'Vogel'}, {'firstname': 'Mark', 'lastname': 'Watney'}] """ # %% Run # - PyCharm: right-click in the editor and `Run Doctest in ...` # - PyCharm: keyboard shortcut `Control + Shift + F10` # - Terminal: `python -m doctest -f -v myfile.py` # %% Imports # %% Types result: str # %% Data # %% Result result = """ SELECT `firstname`, `lastname` FROM `users` WHERE `lastname` """