If you've installed a package but you're getting a ModuleNotFoundError when you try to import it, it's likely that the environment where your code is running is different from the one where you did the installation.
You can read about Python environments at /tag environments and /tag venv.
Common causes of this problem include:
- You installed your package using
pip install .... It could be that thepipcommand is not pointing to the environment where your code runs. For greater control, you could instead run pip as a module within the python environment you specify:python -m pip install <your_package> - Your editor/ide is configured to create virtual environments automatically (PyCharm is configured this way by default).
Don't use f-strings (f"") or other forms of "string interpolation" (%, +, .format) to inject data into a SQL query. It is an endless source of bugs and syntax errors. Additionally, in user-facing applications, it presents a major security risk via SQL injection.
Your database library should support "query parameters". A query parameter is a placeholder that you put in the SQL query. When the query is executed, you provide data to the database library, and the library inserts the data into the query for you, safely.
For example, the sqlite3 package supports using ? as a placeholder:
query = "SELECT * FROM stocks WHERE symbol = ?;"
params = ("RHAT",)
db.execute(query, params)%s and $1. Consult your library's documentation for details.
See Also - Python sqlite3 docs - How to use placeholders to bind values in SQL queries - PEP-249 - A specification of how database libraries in Python should work