SQL = Structure Query Language
Designed for technical & non-technical: query, manipulate, data transform from relational database.
Safe and scalable storage
Relational Database
represents a collection of two-dimensional tables
named columns = attributes/properties of table
rows = data
SELECT
complex clauses can be constructed by joining multiple AND
OR
keywords and with use of operators.
using WHERE
, SQL supports the use of text-data specific operators
DISTINCT
blindly discards rows with duplicate column values
GROUP BY
lets use discard based on specific columns
ORDER BY
allows organization by ascending or descending order. Often used with:
LIMIT
to reduced number of rows to return
OFFSET
to specify where to begin counting of number of rows from
Database Schema describes structure of table and datatypes each table can have.
INSERT
declares which table to write into, columns of data to fill and one + rows of data to insert
UPDATE
similar to INSERT but the data being updated must match data type of columns in table schema
DELETE
describes table to act on and which rows to delete using WHERE
clause.
CREATING
can be made with different table types and each column can have table constraints
ALTER TABLE
to add, remove, or modify columns and constraints
DROP TABLE
different from DELETE because it also removes table schema from database entirely