SQL Developer

SQL (Structured Query Language) is a declarative language commonaly used in RDMS (Relational Database Management Systems). SQL uses a relational (set based) model; objects (tables) are related by key records.

SQL was invented by three men; Raymond Boyce, Donald Messerly and Andrew Richardson, at IBM. SQL and relational databases came about because of Edgar Codd's paper; A Relational Model of Data for Large Shared Data Banks. The Boyce-Codd Normal Form (BCNF), named after Boyce and Codd and created in 1974, is a slightly improved version on the 3^rd normal form. SQL took a while to gain traction, but now it is the dominant language in multiuser database systems.

SQL Uses

SQL is used primarily in Relational Databases, and can generally do most of the tasks required of a database. Tables can be created and related, records inserted and updated, and sets of records selected from many tables. SQL is declarative in nature and so often is supported by a procedural language of each database implementation.

Poised Solutions can develop SQL code for a number of database systems; PostgreSQL, Oracle, Sybase, MySQL, SQLite and SQL Server. SQL is fairly standard across databases, there are nuances in each one but those can generally be translated over with the minimum of fuss.

Databases can be found everywhere where there is a need to share data access and storage amongst a group of people. As the most common modern database is an RDBMS, SQL requirement is present in nearly all IT projects of any size. Ecommerce Development, Web Development, Application Development, Daemon Development (logging), data storage is a common requirement; programs are primarily code and data, the code acts on the data of the system to produce the result.

SQL Example Code

------------------------------------------------------------
--           _            _
--  ___ __ _| |  ___ __ _| |
-- (_-</ _` | |_(_-</ _` | |
-- /__/\__, |_(_)__/\__, |_|
--        |_|          |_|
--
------------------------------------------------------------
-- File      : sql.sql
-- Author    : Richard Lewis
-- Project   : /mnt/webbeastie/proj/poisedsolutions/lib/code/
-- Syntax    : sql
-- Date      : Mon 13 Jul 2009
-- Copyright : Richard Lewis 2009
------------------------------------------------------------
-- sql.sql - sql example file
------------------------------------------------------------

create table person (
    id          bigserial primary key,
    first_name  varchar,
    middle_name varchar[],
    last_name   varchar,
    dob         date,
    created     timestamp
);
------------------------------------------------------------

create table phone_clan (
    id   bigserial primary key,
    clan varchar
);
------------------------------------------------------------

insert into phone_clan
(clan)
select 'land'
union
select 'mobile'
union
select 'web';
------------------------------------------------------------

create table phone (
    id      bigserial primary key,
    clan_id bigint references phone_clan( id ),
    value   varchar
);
------------------------------------------------------------

create table person_phone (
    id        bigserial primary key,
    person_id bigint references person( id ),
    phone_id  bigint references phone( id ),
    unique( person_id, phone_id )
);
------------------------------------------------------------

begin;

insert into person (
    first_name,
    middle_name,
    last_name,
    dob,
    created
)
select
    'John',
    '{"Adrian", "Zachariah"}',
    'Smith',
    '1969-07-07',
    now();

insert into phone (
    clan_id,
    value
)
select
    id, '555 777 999'
from
    phone_clan
where
    clan = 'mobile';

insert into person_phone (
    person_id,
    phone_id
)
select
    currval( 'person_id_seq' ),
    currval( 'phone_id_seq'  );

commit;
------------------------------------------------------------

SQL Development Services Poised Solutions

Development	Database Development

RDBMS Development	PostgreSQL Developer	Oracle Developer

Sybase Developer	Web Development	Ecommerce Development	Daemon Development

SQL Resources

SQL Resources

• SQL Links
• SQL Books