Databases & Data Cheat Sheets
Database shells, SQL and data tools.
MongoDB Shell
MongoDB stores JSON-like documents in collections. mongosh is the modern shell. In examples, db.users means the collection users in the current database.
MySQL & PostgreSQL CLI
The mysql and psql command-line clients side by side. For SQL itself, see the SQL sheet. In psql, backslash commands need no ;. SQL statements always end with ;.
Power BI
Workflow: Get data → clean it in Power Query → build the model (relationships + DAX measures) → design report visuals → publish to the Power BI Service.
SQL
Standard SQL that works in PostgreSQL, MySQL/MariaDB, SQLite and SQL Server (with small differences, noted). Examples use the tables customers(id, name, city) and orders(id, customer_id, total, created_at).