SQL syntax and structure

Introduction to SQL — What is SQL? — History and standards (SQL-92, SQL:2011) — Popular RDBMS: MySQL, PostgreSQL, SQLite, SQL Server — SQL syntax and structure Database Basics — What is a database? — Tables, rows, columns — Primary key and foreign key — Relational model overview Creating and Managing Databases — CREATE DATABASE — USE, DROP DATABASE — Database naming conventions Creating and Managing Tables — CREATE TABLE syntax — Data types (INT, VARCHAR, DATE, etc.) — Constraints (NOT NULL, UNIQUE, DEFAULT) — DROP and ALTER TABLE Inserting Data — INSERT INTO syntax — Inserting single and multiple rows — Using DEFAULT values Querying Data (SELECT) — SELECT basics — Filtering with WHERE — Sorting with ORDER BY — DISTINCT keyword — LIMIT and OFFSET Filtering Data — Comparison operators (=, <>, >, etc.) — Logical operators (AND, OR, NOT) — BETWEEN, IN, LIKE — IS NULL / IS NOT NULL Updating and Deleting Data — UPDATE syntax — DELETE syntax — WHERE clause best practices — TRUNCATE vs DELETE Joins in SQL — INNER JOIN — LEFT JOIN — RIGHT JOIN — FULL OUTER JOIN — Self join and cross join Aggregate Functions — COUNT(), SUM(), AVG(), MIN(), MAX() — GROUP BY and HAVING — Filtering grouped data Subqueries — Subqueries in SELECT, WHERE, FROM — Correlated vs non-correlated subqueries Set Operations — UNION vs UNION ALL — INTERSECT and EXCEPT (if supported) Indexes — What is an index? — CREATE INDEX syntax — Unique index — Performance considerations Constraints and Keys — PRIMARY KEY — FOREIGN KEY — CHECK, DEFAULT — ON DELETE / ON UPDATE CASCADE Views — CREATE VIEW syntax — Updating data through views — Dropping views Stored Procedures — What is a stored procedure? — CREATE PROCEDURE — IN, OUT, INOUT parameters — Calling procedures Functions — User-defined functions (UDFs) — Differences from procedures — RETURN values and syntax Triggers — CREATE TRIGGER syntax — BEFORE / AFTER INSERT, UPDATE, DELETE — Use cases and examples Transactions and ACID — BEGIN, COMMIT, ROLLBACK — SAVEPOINT — Understanding ACID properties User and Permission Management — Creating users — GRANT and REVOKE privileges — Roles and security best practices Normalization and Database Design — 1NF, 2NF, 3NF — Denormalization — Designing efficient schemas Working with Dates and Time — DATE, TIME, DATETIME — DATE functions (NOW(), CURDATE(), DATEDIFF()) Common Built-in Functions — String functions (CONCAT, SUBSTRING, REPLACE) — Math functions (ROUND, FLOOR, CEIL) — Date functions (NOW, DATE_ADD, etc.) Performance Tuning — Query optimization — Using EXPLAIN — Reducing slow queries Real-World Projects — Student/course database — E-commerce schema — Blog or CMS backend — Library/book management system

SQL syntax and structure

Understand SQL syntax and structure in SQL for effective database querying and management.

SQL Syntax and Structure

SQL syntax is the set of rules that defines how SQL statements should be written and structured. Each SQL command typically begins with a keyword such as SELECT, INSERT, UPDATE, etc., and follows a specific format.

1. SELECT Statement
SELECT column1, column2
FROM table_name
WHERE condition
ORDER BY column1 ASC;

Purpose: Retrieves specific data from one or more tables.

2. INSERT Statement
INSERT INTO table_name (column1, column2)
VALUES ('value1', 'value2');

Purpose: Adds new records to a table.

3. UPDATE Statement
UPDATE table_name
SET column1 = 'value1'
WHERE condition;

Purpose: Modifies existing records.

4. DELETE Statement
DELETE FROM table_name
WHERE condition;

Purpose: Removes records based on a condition.

5. CREATE TABLE Statement
CREATE TABLE employees (
  id INT PRIMARY KEY,
  name VARCHAR(100),
  age INT,
  department VARCHAR(50)
);

Purpose: Defines a new table and its structure.

SQL Syntax Rules

  • SQL is case-insensitive, but keywords are usually written in uppercase for readability.
  • Statements end with a semicolon ;.
  • String values are enclosed in single quotes: 'value'.
  • SQL follows a declarative style — you state *what* you want, not *how* to do it.
  • Comments can be added using -- for single line or /* ... */ for block comments.
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