SQL
What is SQL: Databases, DBMS and RDBMS
SQL is the declarative language used to define and query relational data. Start here to see what a database, a DBMS and an RDBMS actually are.
SQL Basics
What SQL is, the relational model, syntax, data types, operators and the sample database used throughout.
6 notes
Notes
SQL
The Relational Model: Tables, Rows, Columns and Schemas
Tables hold typed columns and unordered rows, schemas hold tables, and every value obeys the type its column declares.
SQL
SQL Syntax, Keywords, Identifiers and Comments
How a SQL statement is built: clause order, keywords versus identifiers, quoting rules, statement terminators and the two comment styles.
SQL
SQL Data Types Explained
Numeric, string, date and boolean types across the major dialects, and how to pick the type that stops bad data at the door.
SQL
SQL Operators and Expressions
Arithmetic, comparison, logical, string and set operators, how precedence works, and where an expression may legally appear.
SQL
The Sample Database Used in This Path
Two small schemas - a company HR database and a shop sales database - used by every example in this SQL path. Create them once and follow along.