6 docs tagged with "sql"

Habits that make SQL easier to read, faster, and safe to run — formatting, naming, NULLs, joins, index-friendly filters, safe changes, schema design, migrations, security, testing, and a pre-merge checklist.

How SQL helps test engineers — checking what the app saved, isolated test data, data-quality checks, comparing tables, testing migrations and constraints, waiting for async writes, index checks, and database tests in CI.

How to learn SQL in seven milestones — what to learn in each, the dataset and tasks you work through, how to check yourself, and the role track that follows.

A small dataset and a set of tasks with expected results for each of the seven core SQL milestones — library catalogue, weather report, loans, a to-do schema, customer segments, a leaderboard, and a bank ledger.

Copy-paste SQL reference — clause order, operators, functions, joins, window frames, DDL, types, dialect differences (PostgreSQL, MySQL, SQLite, SQL Server), CLI commands, and handy queries.

End-to-end reference for SQL — DML/DDL, joins, aggregates, subqueries vs CTEs vs window functions, indexes, transactions, and interview-ready Q&A.