treehouse / cheatsheets

Cheat Sheets

A collection of cheat sheets for Treehouse Courses

Databases

• SQL Basics
• Modifying Data With SQL
• Reporting with SQL
• Querying Relational Databases
• Markdown Basics

cheatsheets's Issues

Incomplete sentence

In outer joins example's, last sentence seems to be incomplete:

The following two examples will yield the same results, however one is an

INCOMPLETE: modifying_data_with_sql_orlee_gillis

INTRO TO TRANSACTIONS

AUTOCOMMIT TRANSACTIONS -- DEFINITION:
"Autocommit mode is the default transaction management mode of the SQL Server Database Engine. Every Transact-SQL statement is committed or rolled back when it completes. If a statement completes successfully, it is committed; if it encounters any error, it is rolled back.

A connection to an instance of the Database Engine operates in autocommit mode whenever this default mode has not been overridden by either explicit or implicit transactions." -- Microsoft TechNet

SEED SCRIPT -- DEFINITION:
"A script that populates your database with a set of test data. It can be as simple as a bunch of INSERT statements, or something much more elaborate." -- ycombinator thread

TRANSACTIONS -- DEFINITION + FUNCTION:
-- Used to switch-off 'autocommit'

BEGIN TRANSACTION/BEGIN -- DEFINITION + FUNCTION:
"Start a transaction"

COMMIT (OPERATOR) -- DEFINITION + FUNCTION:
"Commits all transactions since the transaction begin and turns autocommit mode on"

• Cannot be undone.

SEEDING -- DEFINITION + FUNCTION:
"Populating a database for the first time (in the form of a 'Script File')

**'UPDATES' -- DEFINITION + FUNCTIONS:
"Getting rid of changes that haven't been committed yet."

• ROLLBACK (OPERATOR) -- DEFINITION + FUNCTION:
  Undo changes you made.
  Always an option.

SET (OPERATOR) -- DEFINITION + FUNCTION:
Assigning a new VALUE to an existing VALUE

AUTO INCREMENT (OPERATOR) -- DEFINITION + FUNCTION:
Generates the latest ID for you so you don't have to.
Designates the ID column as an 'auto-incremented column'.

OBJECT-RELATIONAL-MAPPING (ORM):
"Used to perform CRUD operations with a language other than SQL."
(Many developers, while using databases, aren't required to write a single line of SQL code. They use special software libraries called ORMs.)

DATA-MANIPULATION-LANGUAGE (DML):