SQL Mastery: The Essential Cheat Sheet for Data Professionals

Whether you're a backend developer, a data analyst, or someone who just needs to pull data from a database without breaking things, SQL is one of those skills that pays dividends every single day. The problem is that the syntax varies across PostgreSQL, MySQL, and SQL Server just enough to trip you up constantly. This cheat sheet covers all three, so you can stop second-guessing your queries. Data Types Key types across PostgreSQL, MySQL, and SQL Server: Integer: INT, BIGINT, SMALLINT (all) Decimal: NUMERIC(p,s) / DECIMAL(p,s) (all) String (variable): VARCHAR(n) (all) Large text: TEXT (PG/MySQL), VARCHAR(MAX) (SQL Server) Boolean: BOOLEAN (PG), TINYINT(1) (MySQL), BIT (SQL Server) Datetime: TIMESTAMP (PG), DATETIME (MySQL/SQL Server) UUID: UUID (PG), CHAR(36) (MySQL), UNIQUEIDENTIFIER (SQL Server) JSON: JSON/JSONB (PG), JSON (MySQL), NVARCHAR(MAX) (SQL Server) DDL -- Define Structure Create Table CREATE TABLE users ( id SERIAL PRIMARY KEY, -- auto-increment (PostgreSQL) username VARCHA