sql overview

eagle rock information systems199 So Los Robles, Suite 860, Pasadena, CA 91101 USA

626-535-9658www.eriscorp.com

SQL Overview

Introduction to SQL for the MultiValue Developer



Why are we here?

• Many MultiValue developers now are working with the various relational databases

• We want to look at common commands and data structures for SQL databases

• We want to see how they relate to the MultiValue



eris

• Database to Web integration since 1992• Customers with up to $2 Billion in annual revenue• Clients throughout North America• Education, Medical, Manufacturing, EDI,

Distribution, Sales Force Automation, Help Desk, and Reporting Systems

• e-Commerce and database product development, e.g., WebWizard, DataReady, mv://e-Store

• Los Angeles and Chicago offices



Agenda

• About eris

• SQL Overview– Basics– Reporting– Database maintenance



What is SQL?

• Standard Query Language

• Used to communicate with the database– Get data– Maintain data– Create data



Standard SQL?

• Not really

• Similar related languages (think Latin)– You need to understand the dialect– Be able to compare what yours has vs others

• Hmm…Think MultiValue



Basic parts of SQL

• Data Definition Language (DDL)

• Database Manipulation Language (DML)

• Database Control Language (DCL)

• Database Stored Procedure Language (DSPL)



Data Definition Language (DDL)

• Defines the database environment• Varies most among the various SQL flavors• Covers

– Database– Design Structures– Related System Tables– Metadata

• Schemas• Catalogs• Stored Procedures• Other structural elements



Database Manipulation Language (DML)

• Reasonably standardized.

• We'll look at DML later on

• Problems arise not in what they offer but what they might not have– Types of joins– Sub-queries



Database Control Language (DCL)

• How to maintain and configure the database

• Permission, roles, and referential integrity– Grant– Check– Constraint– Primary Key– Foreign Key

• Fairly dissimilar among the various flavors



Database Stored Procedure Language (DSPL)

• All the previous variations compound when you get to this section

• Triggers

• Event handler

• Stored procedures

• Can barely compare– Oracle's PL/SQL – SQL Server's Transact SQL – DB2's Stored Procedures



Reporting – Which SQL?

• Microsoft SQL Server

• mySQL

• Oracle

• DB2

• SQLite

• SQLAnywhere

• MultiValue, such as in uniVerse/UniData



What does a table look like?

city state high low

Las Vegas Nevada 115 90

Pasadena California 88 57

Pasadena Texas 92 81

Santa Monica California 77 67

Weather



Lingo

• Row– Record

• Column– Attribute / Field



How do I list?

• Select

• select high, low from Weather where city like “%Pasa%”;

• select * from Weather where city = “California”;



Selecting Data

• “select” is comparable to “LIST”

• Syntax:select column1 [,column2,etc or * for all]

from tablename[where condition] ;

• Compare with – LIST "tablename" "column1" "column2" WITH "condition"



Roster database

first last id age city

Eric Edwards 2101 17 San Diego

John Johnson 1801 17 Pasadena

Sam Joliet 1314 17 Pasadena

Mary Jones 1342 16 Altadena

Eric Taylor 2412 16 Pasadena

Joseph Tyler 1442 17 Pasadena

Janice Williams 1446 16 Pasadena



Sample queries

• select first, last, city from roster;

• select last, city, age from roster where age > 30;

• select first, last, city, state from roster where first like 'J%';

• select * from roster;

• select first, last, from roster where last like '%s';

• select first, last, age from roster where last like '%on%';

• select * from roster where first = 'Eric';



Sample operators in Joins, Where and Having

• And, Or, Not – itemWidth > 11 and itemHeight < 14 – not (region = "E" or sales < quota)

• Is Null, Is Not Null– Nulls occur when no data value has been entered into a

field. Different from MultiValue

• Between– a shorthand way to refer to a range– totalSales between 1500 and 1800



More operators

• In, Not In - allows table lookups– vehicleType in ("sedan", "roadster", "2-door") – sportPlayed not in ("tennis","squash", "badminton",

"raquetball")

• Like– one of the most powerful for searches within a text or

varchar field– Think “…” or “[“ and “]” in MultiValue– Supports text search patterns which work like but not

identically the same in syntax as regular expressions from Unix and XML



Like, Even More Operators

• "%" is any length (think "*" in DOS)

• "_" is a single character (think "?" in DOS)

• [] lists valid characters at the point:[mp]a[nt] can be map, mat, pan, pat[0-9] means a numeric character

• [^] lists excluded characters



Inner Joins

• This is what makes SQL "relational“

• It joins tables

• Similar to translates in MultiValue

• Syntax:

select list-of-columnsfrom tablename1,tablename2where search-condition(s) ;



Imagine an Inner Join

• customers table– customer_id– firstname– lastname– address– city– state – zip

• sales table– sale_id– cust_id– date – Item– price

select customers.firstname, customers.lastname, sales.item

from customers, sales

where customers.customer_id = sales.cust_id;



No need for a new dictionary element

• The columns have the table name in front

• A period separates the table name from the column name– This is opional but is very recommended. It is

required if the name column names are the same between the two tables.



Alternate Syntax


from customers, sales

where customers.customer_id = sales.cust_id;


from customersinner join sales

on customers.customer_id = sales.cust_id;



Database Maintenance

• Creating tables

• Adding records

• Editing records

• Deleting records



Creating tables

• Analogous to CREATE-FILE / CREATE.FILE• Syntax:

create table tablename(column1 datatype, …) ;

• Table and Column names– must start with a letter– can be followed by letters, numbers, or underscores– not to exceed a total of 30 characters in length– Do not use any SQL reserved keywords



Common Data types

char(size) Fixed-length character string. Size is specified in parenthesis. Max 255 bytes.

varchar(size) Variable-length character string. Max size is specified in parenthesis.

number(size) Number value with a max number of column digits specified in parenthesis.

date Date value

number(size,d) Number value with a maximum number of digits of "size" total, with a maximum number of "d" digits to the right of the decimal.



Add records - Insert

• Syntax:

insert into tablename (first_column, ... ,last_column) values (‘first_value’, ... ,’last_value’);

• Strings need single-quotes!

• Example:insert into customers (first, last, age, address, city, state) values ('Joe', 'Johnson', 21, '199 Los Robles', 'Pasadena', 'California');



Updating Records - Update and where

• Syntax:

update tablenameset first_column = new_value[,next_column = newvalue2 …]

where condition [and|or condition2 …];



Examples

• update phone_bookset area_code = 323where prefix = 213;

• update phone_bookset prefix=555, suffix=9292where last_name = 'Jones'and first_name = 'John' ;

• update employeeset age = age+1where first_name='Mary' and last_name='Williams';



Deleting records

• Syntax:

delete from tablenamewhere condition[and|or condition2 …];

• Warning! if you leave off the where clause, all records will be deleted!



Bottom Line

• SQL has the very same intent, functionality, and general purpose across database vendors - users have had to get used to working in dialects.

• SQL interoperability is a problem.

• It provides the Rosetta Stone of a standard, common syntax for data interchange not just between relational databases; but also structured data in general.



Contact us

Main Office: 199 S. Los Robles Ave, Suite 860

Pasadena, CA 91101

Tel: (626) 535-9658 Fax: (626) 628-3229

www.eriscorp.com

info @ eriscorp.com

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