What is SQL Anyway?

Database

A container (usually a file or set of files) to store organized data; a set of related information.

Relational Model

Allows for easy querying and data manipulation in an easy, logical and intuitive way

Relationship

Describes association among entities. one-to-many, many-to-many, one-to-one

Building Block of Relational Models

Entity, Attribute, Relationship

Foreign Key

One or more columns that can be used together to identify a single row in another table

Transactional Model

Operational database- information is not stored in a way that's conducive to querying and analysis.

Retrieving Multiple Columns

Put a comma after each column name SELECT 1 ,2 ,3 From abc;

Limit (get a sample of data)

SELECT * FROM abc LIMIT 5;

Request all columns

SELECT * FROM abc;

Select Statement

SELECT-either all or particular columns from a table in a query FROM- tell the database which table your data is coming from

ER Diagrams

Show relationships, Business Process, represented visually, show links (primary keys)

Understand Your Data

Understand the business process or subject matter the data is modeled after, know the business rules, understand how your data is organized and structured in the table (modeled)

Think Before you Code

What is the problem you are trying to solve?

Attribute

a characteristic of an entity

Primary Key

a column (or set of columns) whose values uniquely identify every row in a table

NoSQL (Not Only SQL)

a mechanism for storage and retrieval of unstructured data modeled by means other than tabular relations in relational databases

Row

a record in a table

Column

a single field in a table-all tables are made up of one or more columns

Tables

a structured list of data or a specific type

Structured Query Language (SQL)

is a standard computer language for relational database management and data manipulation. Used to query, insert, update and modify data.

ER model

is composed of entity types and specifies relationships that can exist between instances of those entity types

Two types of Data Models

models for prediction built by data scientists and data tables represented and organized in a database

SQL is a

non-procedual language- cannot write complete applications.

What is Data Modeling?

organizes and structures information into multiple, related tables, can represent a business process or show relationships between business processes, should closely represent real world

Entity

person, place, thing or event. Distinguishable, unique, and distinct.

SQL is used to

read/retrieve data, write data, and update data

How do data scientist use SQL?

retrieve data, may create their own table or test environment, combine multiple sources together, writes complex queries for analysis

What is SQL?

used to communicate with databases. Statements are made up of descriptive words and are easy to learn