SQL notes - This note is based on SQL w3school tutorial PDF

Preview

Summary

This note is based on SQL w3school tutorial...

Description

W3School Tutorial: https://www.w3schools.com/sql/default.asp

SQL syntax Semicolon “;” is needed after each statements. SQL requires single quotes ‘’ around text values, numeric fields with no quotes

Some of The Most Important SQL Commands:           

SELECT - extracts data from a database UPDATE - updates data in a database DELETE - deletes data from a database INSERT INTO - inserts new data into a database CREATE DATABASE - creates a new database ALTER DATABASE - modifies a database CREATE TABLE - creates a new table ALTER TABLE - modifies a table DROP TABLE - deletes a table CREATE INDEX - creates an index (search key) DROP INDEX - deletes an index

Single Line Comments:  

start with – Any text between -- and the end of the line will be ignored

Multi-line Comments:  

start with /* and end with */ Any text between /* and */ will be ignored

Arithmetic Opetators:     

+ : add - : subtract * : multiply / : divide % : modulo

Comparison Operators:      

= : equal > : greater than < : less than >= : greater than or equal =,...