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[Nomad PHP EU] Introduction to Databases

Davey Shafik
November 14, 2013

[Nomad PHP EU] Introduction to Databases

This talk will cover the basics necessary to help you decide what data to store, where, and how.

We will cover PDO — PHP’s Data Object extension, which allows you to talk to a variety of databases, including MySQL.

You will learn how to CRUD — Create, Retrieve, Update and Delete data, database schema, and when to use indexes.

Additionally, we will look at other data storage systems such as memcache, and nosql databases.

Davey Shafik

November 14, 2013
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  1. •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 1 & 2, phpdoc, and PHP internals • @dshafik Davey Shafik
  2. 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)
  3. 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 !7
  4. 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 !9
  5. 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 !11
  6. 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 !13
  7. 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 !15
  8. 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
  9. Users Table • Unique Identifier • Username • Password •

    Email Address • Name or First Name/Last Name !21 Consider: • Column Names • Column Types • Column Lengths
  10. Users Table !22 Users id int username varchar(20) password varchar(60)

    email varchar(150) first_name varchar(45) last_name varchar(55)
  11. Users Table !23 Users id int username varchar(20) password varchar(60)

    email varchar(150) first_name varchar(45) last_name varchar(55) CREATE TABLE ( , , , , , );
  12. 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) );
  13. SQL • INSERT — Create Data • UPDATE — Update

    Existing Data • SELECT — Fetch Data • DELETE — Delete Data !26 Four Main Queries
  14. Conditions • Used with: • SELECT • UDPATE • DELETE

    • JOINs • Preceded by the WHERE, ON, or USING keyword !30
  15. Operators !31 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
  16. INSERT INSERT INTO table name ( list, of, columns )

    VALUES ( "list", "of", "values" ); !33
  17. 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" ); !34
  18. SELECT SELECT list, of, columns FROM table WHERE column =

    "some" AND name = "value" OR other_column = "other value" ORDER BY some ASC, columns DESC LIMIT start, end;
  19. SELECT SELECT    *   FROM    users   WHERE

       username  =  "davey"    AND  password  =  "$2y$10$Ol..."   LIMIT  1;
  20. DELETE DELETE FROM table WHERE column = "some" AND name

    = "value" OR other_column = "other value" ORDER BY some ASC, columns DESC LIMIT number;
  21. 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 !50
  22. Constraints: Users Table !51 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
  23. 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) );
  24. 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)
  25. Features: Users Table •ID should be auto increment •ID should

    be the Primary Key •ID should be unsigned !55
  26. 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) );
  27. Indexes !58 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
  28. 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! !60
  29. 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 !62
  30. Profiles Table • Unique Identifier • Short Introductory Summary •

    Full Biography • Location !64 Consider: • Must link to the Users table • One Profile per User
  31. Profiles Table 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
  32. 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 );
  33. INSERT INSERT INTO profiles ( users_id, summary, bio, location )

    VALUES ( 1, "Community Engineer at Engine Yard", NULL, "Florida, USA" );
  34. 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%) !70
  35. Indexes • Add Indexes to the users table • Remember

    we already have a PRIMARY KEY and UNIQUE indexes • Example queries we will perform against it: !72 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%";
  36. Indexes !73 Users Key Type id PRIMARY KEY username UNIQUE

    username, password UNIQUE email UNIQUE
  37. LEFT OUTER JOIN For when one side or the other

    doesn’t match Users Users with Profiles Profiles
  38. 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;
  39. SELECT... LEFT OUTER JOIN SELECT * FROM users LEFT OUTER

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

    JOIN profiles ON ( profiles.user_id = users.id ) RIGHT OUTER JOIN posts ON ( posts.user_id = users.id ) WHERE posts.content LIKE '%PHP%';
  41. 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 • Password • Database Name • Charset • Connecting • new PDO() • Disconnecting • PDO::__destruct() !85
  42. Executing Queries <?php $pdo = new PDO(...); $query = $pdo->prepare(

    "SELECT * FROM user WHERE id = :id" ); $conditions = array( ':id' => 1 ); $result = $query->execute($conditions); ?>
  43. Handling Results <?php $result = $query->execute($conditions); if ($result) {
  

     echo  "Results  Found:  "  .$query-­‐>rowCount(); while ($row = $query->fetch()) { echo "<a href='/edit/" .$row['id']. "'>" .$row['first_name']. ' ' . $row['last_name'] .'</a>'; } } ?>
  44. Handling Results as Objects <?php $result = $query->execute($conditions); if ($result)

    { echo  "Results  Found:  "  .$query-­‐>rowCount(); while ($row = $query->fetchObject()) { echo "<a href='/edit/" .$row->id. "'>" .$row->first_name. ' ' . $row->last_name .'</a>'; } } ?>
  45. 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 = $query->fetchObject("User")) { echo "<a href='/edit/" .$row->id. "'>" .$row->getName(). '</a>'; } }