Introduction to Databases

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Databases Getting Started with Data

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•Community Engineer at Engine Yard •Author of Zend PHP 5 Certification Study Guide, Sitepoints PHP Anthology: 101 Essential Tips, Tricks & Hacks & PHP Master: Write Cutting Edge Code •A contributor to Zend Framework, phpdoc, FRAPI and PHP internals •@dshafik Davey Shafik

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About These Slides

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About These Slides • Two slides per “slide” • Title Slide (for when I’m talking) • Details slide (for later) • Nobody likes it when you can read the slide just as well as the speaker can • I like slides that are useful 4

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What is a Database?

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What is a Database? A database is an organized collection of data. The data is typically organized to model relevant aspects of reality, in a way that supports processes requiring this information. “ ” Source: Wikipedia (Emphasis Mine)

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Types of Database

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SQL (Relational)

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SQL (Relational) • Highly Structured Data • Using Tables, Columns and Rows • One or more relationships exist between datas • Constraints • Primary Keys (a unique row identiﬁer) • Unique Keys (one or more columns that must have unique values, either individually, or as a group) • Foreign Keys (a column value that must be derived from a column value in another table) • Indexes • A lookup for one, or multiple columns aggregate data 9

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NoSQL (Document/Key-Value/Graph)

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NoSQL (Document/Key-Value/Graph) • Sometimes called “Not Only SQL” because some NoSQL DBs have a SQL-like query language • Not always non-relational • Always unstructured • Intended to provide higher scalability and higher availability • Looser consistency models 11

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Non-Relational Document Stores / Key-Value Stores

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NoSQL (Document/Key-Value/Graph) • NoSQL is non-relational • Document Stores • Centers around the concept of a document, and it’s related meta-data • Collections of documents • Hierarchies of documents • Examples: Couchbase Server, CouchDB, MongoDB, Amazon SimpleDB, Oracle NoSQL DB • Key-Value Stores • Data stored and accessible directly by a unique key • Examples: Memcache, MongoDB, Couchbase Server, Cassandra, Riak, Amazon DynamoDB, Redis, Oracle NoSQL DB 13

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Relational Graph Databases

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NoSQL (Document/Key-Value/Graph) • NoSQL is relational (say what?!) • Graph Databases • All data is related to N other data • Relationships are in the data, not indexes • Examples: OQGraph for MySQL • Example Implementation: Facebook’s Graph API 15

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Relational Concepts

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Relational Concepts • Schema • Tables • Indexes • Relationships • Stored Procedures • Triggers 17

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A Note about MySQL

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A Note on MySQL • MySQL supports multiple drivers (called engines) for it’s tables. • These engine provide different features. • The two most common are InnoDB (default since MySQL 5.5) and MyISAM (previously the default). • InnoDB has far more features, and is recommended for almost all situations • We will assume InnoDB for all MySQL examples 19

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Data Types

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Name What Notes int exact whole numbers Signed or unsigned decimal exact decimal numbers (fixed length) Signed or unsigned float approximate decimal number (variable length) Signed or unsigned char strings (fixed length) Max size: 255 bytes varchar strings (variable length) Max size: 255 bytes text strings (variable length) Max size: 255 bytes - 4GB blob binary strings (variable length) Max size: 255 Bytes - 4GB date dates (no time) Any date is valid datetime dates (with time) Any date/time is valid timestamp timestamp UNIX timestamp, must be > 1/1/1970 NULL Null values Does not equal anything, even NULL

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Exercise One Create a Users Table

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Exercise One: Users Table • Unique Identiﬁer • Username • Password • Email Address • Name or First Name/Last Name 23 Consider: • Column Names • Column Types • Column Lengths

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Exercise One: Users Table 24 Users Users id int username varchar(20) password varchar(60) email varchar(150) ﬁrst_name varchar(45) last_name varchar(55)

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Exercise One: Users Table (Schema) CREATE TABLE users ( id INT, username VARCHAR(20), password VARCHAR(60), email VARCHAR(150), first_name VARCHAR(45), last_name VARCHAR(55) );

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SQL Structured Query Language

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SQL • INSERT — Create Data • UPDATE — Update Existing Data • SELECT — Fetch Data • DELETE — Delete Data 27 Four Main Queries

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CRUD Also Known As:

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CRUD 29 Create INSERT R etrieve SELECT Update UPDATE Delete DELETE

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Conditions

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Conditions • Used with: • SELECT • UDPATE • DELETE • JOINs • Preceded by the WHERE, ON, or USING keyword 31

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Operators 32 Operator = Equality <>, != Inequality < Less Than <= Less Than or Equal To > Greater Than >= Greater Than or Equal To IS NULL NULL Equality IS NOT NULL NULL Inequality AND Boolean AND OR Boolean OR BETWEEN Range Equality

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INSERT

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INSERT INSERT INTO table name ( list, of, columns ) VALUES ( "list", "of", "values" ); 34

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INSERT INSERT INTO users ( id, username, password, email, first_name, last_name ) VALUES ( 1, "dshafik", "$2y$10$Ol/KS4/Bhs5ENUh7OpIDL.Gs1SIWDG.rPaBkPAjjQ2UTITI60YDmG ", "[email protected]", "Davey", "Shafik" ); 35

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UPDATE

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UPDATE UPDATE table name SET column = "some", name = "value" WHERE some condition;

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WARNING: Don’t forget your conditions! Otherwise you update every row in the table!

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UPDATE UPDATE users SET username = "davey", email = "[email protected]" WHERE id = 1;

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SELECT

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SELECT SELECT list, of, columns FROM table WHERE column = "some" AND name = "value" OR other_column = "other value" ORDER BY some, columns LIMIT start, end;

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SELECT SELECT * FROM users WHERE username = "davey" AND password = "$2y$10$Ol..." LIMIT 1;

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SELECT SELECT first_name, last_name, email FROM users ORDER BY first_name, last_name LIMIT 0, 10;

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SELECT SELECT first_name, last_name, email FROM users ORDER BY first_name, last_name LIMIT 10, 20;

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DELETE

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DELETE DELETE FROM table WHERE column = "some" AND name = "value" OR other_column = "other value" ORDER BY some, columns LIMIT number;

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DELETE DELETE FROM users;

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DELETE DELETE FROM users WHERE id = 1;

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Constraints

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Constraints: Users Table • IDs should be unique • Usernames should be unique • Passwords should not be unique • Email Address should be unique • First Name should not be unique • Last Name should not be unique • All column should not be NULL 51

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Constraints: Users Table 52 Users Users Constraints id int unique, not null username varchar(20) unique, not null password varchar(60) not null email varchar(150) unique, not null ﬁrst_name varchar(45) not null last_name varchar(55) not null

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Constraints: Users Table Schema CREATE TABLE users ( id INT NOT NULL, username VARCHAR(20) NOT NULL, password VARCHAR(60) NOT NULL, email VARCHAR(150) NOT NULL, first_name VARCHAR(45) NOT NULL, last_name VARCHAR(55) NOT NULL, UNIQUE INDEX id_UNIQUE (id), UNIQUE INDEX username_UNIQUE (username), UNIQUE INDEX email_UNIQUE (email) );

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Features

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Name What Notes Auto Increment (auto_increment) Automatically inserts the (last row)+1 value when inserting • Column must be set as PRIMARY KEY • One Per Table Signed/Unsigned Sets Numeric columns to signed (may be positive or negative) or unsigned (must be positive) Unsigned numbers start at 0 and allow for much larger numbers. Zero Fill (zeroﬁll) Left Pads numeric values to the column size Only applied on retrieval (i.e. it’s not stored this way)

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Features: Users Table •ID should be auto increment •ID should be the Primary Key •ID should be unsigned 56

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Features: Users Table Schema CREATE TABLE users ( id INT UNSIGNED NOT NULL AUTO_INCREMENT, username VARCHAR(20) NOT NULL, password VARCHAR(60) NOT NULL, email VARCHAR(150) NOT NULL, first_name VARCHAR(45) NOT NULL, last_name VARCHAR(55) NOT NULL, UNIQUE INDEX username_UNIQUE (username), UNIQUE INDEX email_UNIQUE (email), PRIMARY KEY (id) );

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Indexes

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Indexes 59 Name Constraints Notes Index None May have NULL values Unique Unique May have NULL values Primary Key Unique Must NOT have NULL values. May auto_increment. There can only be one. Foreign Key Must match data in linked table May have NULL values

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INDEX, UNIQUE, & PRIMARY KEY

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INDEX, UNIQUE, & PRIMARY KEY • Can be added during table creation: • CREATE TABLE foo ( column_name TYPE, INDEX name (column, list), UNIQUE name (column, list), PRIMARY KEY (column) ); • Index/Unique can have multiple columns • Can be added after table creation: • CREATE INDEX name ON table_name (column, list); ALTER TABLE table name ADD INDEX (column, list); CREATE UNIQUE INDEX name ON table (column, list); ALTER TABLE table name ADD UNIQUE (column, list); ALTER TABLE table name ADD PRIMARY KEY (column); • Must be added with caution! 61

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Foreign Keys

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Foreign Keys • Used to create inter-table relationships • Value must be in the foreign table or NULL • Can update when the foreign table updates • Can delete when the foreign table deletes • Can be set to NULL when the foreign table deletes 63

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Exercise Two Proﬁles & Foreign Keys

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Exercise Two: Profiles Table • Unique Identifier • Short Introductory Summary • Full Biography • Location 65 Consider: • Must link to the Users table • One Profile per User

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Exercise Two: Profiles Table Profiles Profiles Constraints id int UNSIGNED primary key, auto_increment, not null users_id int UNSIGNED unique, foreign key -> users.id, not null summary varchar(200) none bio TEXT none location varchar(100) none

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Exercise Two: Proﬁles Table Schema CREATE TABLE profiles ( id INT UNSIGNED NOT NULL AUTO_INCREMENT, users_id INT UNSIGNED NOT NULL, summary VARCHAR(200) NOT NULL, bio TEXT NULL, location VARCHAR(150) NULL, PRIMARY KEY (id), UNIQUE INDEX users_id_UNIQUE (users_id), CONSTRAINT FOREIGN KEY (users_id) REFERENCES users (id) ON DELETE CASCADE );

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INSERT INSERT INTO profiles ( users_id, summary, bio, location ) VALUES ( 1, "Community Engineer at Engine Yard", NULL, "Florida, USA" );

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Indexing Your Data

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Indexing Your Data • Indexes make writes slower, and reads (much faster). The more indexes, the slower your writes. • The creation of indexes should be determined by the SELECT queries being run upon the data. Nothing else. • For example, if you run a query that SELECTs using two WHERE criteria with an AND condition, that is probably a good combination index. • MySQL can only use one index [per table] at a time and will (generally) pick the best option based on the query • Indexes cannot be used with LIKE if starting with a wildcard (e.g. %foo%) 71

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Exercise Three Indexes

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Exercise Three: Indexes • Add Indexes to the users table • Remember we already have a PRIMARY KEY and UNIQUE indexes • Example queries we will perform against it: 73 SELECT * FROM users WHERE username = "davey" AND password = "$2y$10$Ol..."; SELECT * FROM users WHERE email = "[email protected]"; SELECT * FROM users WHERE first_name LIKE "%Dave%";

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Exercise Three: Indexes 74 Users Users Key Type id PRIMARY KEY username UNIQUE username, password UNIQUE email UNIQUE

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JOINs Connecting Tables

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JOINs • Used to JOIN multiple tables • INNER JOIN • LEFT or RIGHT OUTER JOIN 76

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INNER JOIN Get the intersection of two tables Users Proﬁles Users with Proﬁles

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OUTER JOIN For when one side or the other doesn’t match

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LEFT OUTER JOIN For when one side or the other doesn’t match Users Users with Proﬁles Proﬁles

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RIGHT OUTER JOIN Users Proﬁles with Users Proﬁles

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SELECT... INNER JOIN SELECT * FROM users INNER JOIN profiles ON ( profiles.user_id = users.id ) WHERE profiles.location LIKE '%Dallas%' ORDER BY users.first_name, users.last_name;

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SELECT... LEFT OUTER JOIN SELECT * FROM users LEFT OUTER JOIN profiles ON ( profiles.user_id = users.id ) WHERE users.id = 1;

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SELECT... RIGHT OUTER JOIN SELECT * FROM users RIGHT OUTER JOIN profiles ON ( profiles.user_id = users.id ) WHERE profiles.bio LIKE '%PHP%';

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Databases and PHP

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Connecting to Databases Using PDO

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Connecting to Databases • PDO • MySQL • PostgreSQL • MSSQL • Oracle • SQLite • ODBC and DB2 • Firebird • DSN — Data Source Name • Driver Name • Hostname & Port • or • Unix Socket • Username 86

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Connecting to MySQL

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Querying Data

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Executing Queries prepare( "SELECT * FROM user WHERE id = :id" ); $conditions = array( ':id' => 1 ); $result = $query->execute($conditions); ?>

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Handling Results

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Handling Results execute($conditions); if ($result) { echo "Results Found: " .$query-‐>rowCount(); while ($row = $query->fetch()) { echo "" .$row['first_name']. ' ' . $row['last_name'] .''; } }

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Handling Results as Objects execute($conditions); if ($result) { echo "Results Found: " .$query-‐>rowCount(); while ($row = $query->fetchObject()) { echo "" .$row->first_name. ' ' . $row->last_name .''; } }

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Handling Results as Custom Objects class User { function getName() { return $this->first_name . ' ' . $this->last_name; } } if ($result) { echo "Results Found: " .$query-‐>rowCount(); while ($row = $query->fetchObject("User")) { echo "" .$row->getName(). ''; } }

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Thank You Feedback: http://joind.in/8703 Twitter: @dshaﬁk Email: [email protected] Slides: http://daveyshaﬁk.com/slides