This document provides an overview of SQL, detailing its definition as a standard language for accessing relational database management systems, along with its various components including data definition, manipulation, and control languages. It covers the history of SQL, evolution of standards over the years, and the structure and types of SQL environment. Additionally, it explains SQL language elements, common data types, and examples of SQL commands and error handling.

1. SQL Fundamentals

2. © copyright : spiraltrain@gmail.com
Course Schedule
• SQL Intro
• SQL Select Queries
• SQL Data Definition
• SQL Functions
• SQL Data Manipulation
• SQL Joins
• What is SQL?
• History of SQL
• SQL Standard
• SQL Parts
• SQL Environment
• Database Creation
• DDL Create Table
• SQL Data Types
• SQL Language Elements
• DML Insert Into
• SQL Errors
• Select Query
2

3. www.spiraltrain.nl
What is SQL?
• Abbreviation of Structured Query Language :
• Standard language to access relational database management systems (RDBMS)
• Actually three languages can be distinguished
• Declarative query language with procedural elements :
• Used to create database schemas and to insert, update, delete and query data
• Data Definition Language (DDL) :
• Language that defines database structure (relation schemas)
• This includes creating, altering, and dropping tables and establishing constraints
• Data Manipulation Language (DML) :
• Query language to create, read, update and delete tuples (CRUD operations)
• Data Control Language (DCL) :
• Used to controls a database includes administering privileges and committing data
• SQL language further deals with the following issues :
• Transaction control , integrity constraints, views, embedded SQL and dynamic SQL
3SQL Intro

4. www.spiraltrain.nl
History of SQL
• SQL started with name SEQUEL in the 1970's :
• Abbreviation of structured english query language
• Developed by Raymond F. Boyce and Donald D. Chamberlin
• Access data stored in IBM's System R relational database
• In 1979 Oracle introduced first commercial version of SQL :
• Oracle V2 (Version2) for VAX computers.
• In 1986 SQL first became an ANSI standard :
• SQL-89 known as SQL 1 was rather incomplete
• SQL-92 is known as first solid standard known as SQL 2
• SQL-99 known as SQL 3 :
— Recursive queries, triggers, object-oriented features
• SQL-2003 :
— Window functions, XML-related features
• SQL-2006 offers XML Query Language (XQuery) support
• SQL-2011 has improved support for temporal databases
SQL Intro 4

5. www.spiraltrain.nl
SQL Standard
• SQL is standard but is not completely portable among RDBMS :
• This is caused by ambiguities and vendor extensions
• Specific SQL implementation by database vendor is SQL dialect
• Vendors implement parts of the SQL standard, e.g. most implement SQL-92
• Vendors add their vendor-specific extensions
• Most vendors conform to a set of Core SQL features :
• Portability might still be limited due to missing or additional features
• Purpose of SQL-92 and SQL-99 Standards :
• Specify syntax/semantics for data definition and manipulation
• Define data structures
• Enable portability
• Specify minimal (level 1) and complete (level 2) standards
• Allow for later growth/enhancement to standard
5SQL Intro

6. www.spiraltrain.nl
SQL Parts
6SQL Intro

7. www.spiraltrain.nl
SQL Environment
• Catalog :
• A set of schemas that constitute the description of a database
• Schema :
• Structure containing descriptions of objects created by a user
• This includes base tables, views, constraints
SQL Intro 7

8. www.spiraltrain.nl
Database Creation
• Creating of database differs for different relational databases :
• Often done through a GUI interface particular for a database
• According to the SQL standard :
• SQL environment contains one or more catalogues :
• Each catalogue manages various metadata :
• Set of schemas consisting of :
— Relations/tables
— Views
— Assertions
— Indexes
• Users and user groups
• Many database use client-server model :
• You must connect to a remote host on certain port, log in and manage database
• SQLite database does not use this model, databases are files
8SQL Intro
Demo01
Create Database

9. www.spiraltrain.nl
DDL Create Table
• Relational databases contain data in tables :
• Uniquely identified by their names and are comprised of columns and rows
• Columns contain the column name, data type, and other attributes
• Rows contain the records or data for the columns
• Tables are created through CREATE TABLE statement of SQL DDL :
CREATE TABLE inventory (
StockNumber INTEGER PRIMARY KEY,
Descrip VARCHAR(50),
OnHandQuan INTEGER,
PackQty INTEGER,
PackCost FLOAT
);
• Typically columns are created of certain data type
9SQL Intro
Demo02
DDL Create Table

10. www.spiraltrain.nl
SQL Data Types
• Columns in a table are of certain data type :
• Often used data types are character strings, numbers and date types
• Character String types :
• CHAR(n) – fixed-length character data, n characters long bytes
• VARCHAR(n) – variable length character data
• LONG – variable-length character data
• Numeric types :
• NUMBER(p,q) – general purpose numeric data type
• INTEGER(p) – signed integer, p digits wide
• INTEGER - signed integer
• FLOAT(p) – floating point in scientific notation with p binary digits precision
• FLOAT – floating point in scientific notation
• Date/time type :
• DATE – fixed-length date/time in dd-mm-yy form
10SQL Intro

11. www.spiraltrain.nl
SQL Language Elements
• Clauses :
• Constituent components of statements and queries, in some cases optional
• Expressions :
• Can produce either scalar values, or tables consisting of columns and rows of data
• Predicates :
• Specify conditions that can be evaluated to true, false or unknown) values
• Used to limit the effects of statements and queries or to change program flow
• Queries :
• Retrieve the data based on specific criteria
• Statements :
• May have a persistent effect on schemata and data
• May control transactions, program flow, connections, sessions or diagnostics
• SQL statements also include the semicolon (";") statement terminator
• Insignificant whitespace is generally ignored :
• Makes it easier to format SQL code for readability
11SQL Intro

12. www.spiraltrain.nl
DML Insert Into
• Database table is filled with SQL INSERT INTO statements :
INSERT INTO inventory(StockNumber,Descrip,OnHandQuan,PackQty,PackCost)
VALUES (51002,'AA Dry Cells 4 Pack',173,12,9.00);
INSERT INTO inventory(StockNumber,Descrip,OnHandQuan,PackQty,PackCost)
VALUES (51004,'AA Dry Cells 8 Pack',5,12,16.80);
INSERT INTO inventory(StockNumber,Descrip,OnHandQuan,PackQty,PackCost)
VALUES (43512,'10W-30 Motor Oil, Quart',36,12,18.20);
INSERT INTO inventory(StockNumber,Descrip,OnHandQuan,PackQty,PackCost)
VALUES (51013,'D Dry Cells 8 Pack',19,12,90.20);
INSERT INTO inventory(StockNumber,Descrip,OnHandQuan,PackQty,PackCost)
VALUES (23155,'Shovel Pointed Long Handle',1500,1,9.82);
INSERT INTO inventory(StockNumber,Descrip,OnHandQuan,PackQty,PackCost)
VALUES (51001,'AAA Dry Cells 4 Pack ',92,12,9.00);
INSERT INTO inventory(StockNumber,Descrip,OnHandQuan,PackQty,PackCost)
VALUES (43111,'White Gas Gallon Can',14,4,14.75);
• Values listed in INSERT INTO statement :
• Must be in the same order as appearing in CREATE TABLE
• Character strings are surrounded with quotes, number not
12SQL Intro
Demo03
DML Insert Values

13. www.spiraltrain.nl
SQL Errors
• SQL State Error Codes are defined by ISO/ANSI SQL Standards :
• 5-character string consisting of 2-characters followed by 3-character subclass value
• "00" indicates success, "01" indicates a warning
• Other class values normally indicate an exception
• Example Error Code :
• SQL0208 - ORDER BY column not in result table
• Typical error is duplicate primary key error :
• Trying to insert row with key already present
13SQL Intro
Demo04
Duplicate Key Error

14. www.spiraltrain.nl
Select Query
• SELECT clause is used to retrieve data from database tables :
SELECT StockNumber,Descrip,OnHandQuan,PackQty,PackCost from inventory
• SELECT is followed by column names separated by comma’s
• Alternatively wild cards may be used to retrieve all columns :
SELECT * FROM inventory;
• SELECT can be combined with clauses WHERE, ORDER_BY etc.
14SQL Intro
Demo05
Select Query

15. © copyright : spiraltrain@gmail.com
Summary : SQL Intro
• SQL is a declarative language to access RDBM Systems :
• Used to create database schemas and to query insert, update and delete data
• SQL is standard but is not completely portable among RDBMS’s :
• This is caused by ambiguities and vendor extensions
• SQL consists of three parts :
• Data definition, data manipulation and data control language
• SQL consist of several language elements :
• Clauses, expressions, predicates, queries and statements
• SQL Environments have catalogues with schema’s and users :
• Each schema defines tables, relations, views, assertions and indexes
• SQL Standard defines SQL State Error Codes :
• 5-character string consisting of 2-characters followed by 3-character subclass value
• SQL Standard defines data types :
• Columns in tables are of a certain data type
SQL Intro 15
Exercise 1
SQL Intro