From 0b357a1e285ecce30f27ef477fbf5b63834fcdd7 Mon Sep 17 00:00:00 2001
From: mo khan <mo.khan@gmail.com>
Date: Tue, 21 Jan 2020 19:26:40 -0700
Subject: Start notes for unit 5

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@@ -10,6 +10,118 @@ Read Chapter 6: Introduction to SQL
 * The SQL Environment
 * Defining a database in SQL
 
+ANSI SQL was first published in 1986.
+Updated in:
+
+* 1989
+* 1992
+* 1999
+* 2003
+* 2006
+* 2008
+
+Concepts were first articulated in 1970 by E.F. Codds paper
+"A Relational Model of Data for Large Shared Data Banks".
+
+IBM devs started to build System R which was to demo an
+implementation of a relational model in a dbms.
+
+They used a language named "Sequel" which was renamed SQL.
+
+SQL/DS: the first relational DBMS.
+DB2: introduced in 1983
+
+Original purpose of SQL standard:
+
+1. specify syntax and semantics of SQL DDL and DML
+2. define data structures and basic operations for designing, accessing, maintaining, controlling and protecting a SQL database.
+3. portability between database definition and application modules between DBMS's.
+4. Specify minimal and complete standards
+5. Extension point for handling referential integrity, transaction management, user defined functions, join operators and character sets.
+
+A standard provides
+
+* Reduced training costs
+* Productivity
+* Application portability
+* Application longevity
+* Reduced dependence on a single vendor
+* Cross system communication
+
+The SQL Environment
+
+SQL is used to:
+
+* create tables
+* translate user requests
+* maintain data dictionary and system catalog
+* update and maintain the tables
+* establish security
+* carry out back and recovery procedures
+
+
+> RDBMS: a database management system that manages data as a collection of tables in which all data relationships are represented by common values in related tables.
+
+Each database is contained in a catalog, which describes any object that is a part of the database.
+
+> Catalog: A set of schemas that, when put together, constitute a description of a database.
+
+> Schema: A structure that contains descriptions of objects created by a user, such as base tables, views and constraints as part of a database.
+
+
+Each catalog must also contain an information schema.
+
+* tables
+* views
+* attributes
+* privileges
+* constraints
+* domains
+
+SQL commands can be classified into three types:
+
+1. DDL: Data definition language
+2. DML: Data manipulation language
+3. DCL: Data control language
+
+> DDL: Commands used to define a database, including those for creating, altering and dropping tables and establishing constraints.
+> DML: Commands used to maintain and query a database, including those for updating, inserting, modifying and querying data.
+> DCL: Commands used to control a database, including those for administering privileges and committing (saving) data.
+
+Each DBMS has a defined list of data types that it can handle.
+
+* numeric
+* string
+* date/time
+* graphic data
+* spatial data
+* image data
+
+Defining a database in SQL
+
+```sql
+CREATE SCHEMA database_name;
+AUTHORIZATION owner_user mokha;
+```
+
+To define a portion of a database that a particular user owns.
+
+```sql
+CREATE SCHEMA
+```
+
+To define a new table and columns
+
+```sql
+CREATE TABLE
+```
+
+To define a new view
+
+```sql
+CREATE VIEW
+```
+
 ## Section 2: SQL as a Data Manipulation Language (DML)
 
 Read Chapter 6: Introduction to SQL
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