Download Lecture 6 Data Model Design

Data Model / Database
Implementation
Jeffery S. Horsburgh
Hydroinformatics
Fall 2015
This work was funded by National
Science Foundation Grants EPS 1135482
and EPS 1208732
Objectives
• Understand common relational database
software packages, limitations and capabilities
• Where are relational databases commonly used?
• Why and when would you use relational
databases?
• Introduce MySQL functionality
• Create a physical implementation of an
Observations Data Model (ODM) database within
a RDBMS
Where We are Going
• Last week: Data Model/Database design
– How do you design a data model for implementation
within a relational database management system
• This week: Database implementation
– How do you physically implement a data model as a
database and load data
• Next week: Using Structured Query Language (SQL)
– Using code to slice and dice your data once you have it in a
database
• A little later: Accessing databases from client software
– Getting data from a database into Python
Steps in Data Model Design
1. Identify entities
2. Identify relationships among entities
3. Determine the cardinality and participation
of relationships
4. Designate keys / identifiers for entities
5. List attributes of entities
6. Identify constraints and business rules
7. Map 1-6 to a physical implementation
Physical Data Model
• The “physical” means a specific implementation
of the data model
– Choice of hardware and operating system
– Choice of relational database management system
– Implementation of tables, relationships, constraints,
triggers, indices, data types
– Database access and security
– Performance
– Storage
Summary of 3 Levels of Data Model Design
Feature
Conceptual
Logical
Entity Names
X
X
Entity Relationships
X
X
Physical
Attributes
X
Primary Keys
X
X
Foreign Keys
X
X
Table Names
X
Column Names
X
Column Data Types
X
Views
X
Stored Procedures
X
Triggers
X
Constraints
X
Relational Database Management Systems
• Robust software for managing data
• Data stored in tables that may be related
• Based on Structured Query Language (SQL)
– Adopted by the American National Standards
Institute (ANSI) and the International Standards
Organization (ISO) as the standard data access
language
Relational Database Management
Systems (RDBMS)
•
•
•
•
•
File vs. server based
Free vs. commercial
Different data types
Potentially different syntax for SQL queries
Security models and concurrent users
File Versus Server-Based RDBMS
• File-based
– Everything contained within a single file
– Generally good for single user, desktop applications
– Examples: SQLite, Microsoft Access
• Server-based
– A database “server” manages databases and all
transactions
– Good for multiple, simultaneous connections and
transactions
– Examples: Oracle, Microsoft SQL Server, MySQL,
PostgreSQL
The Beauty of Server-Based RDBMS
Data
Database
Authentication and Access Control
Yay!
I want some
Database ServerDo I know you?Do I recognize
data!
Are you your IP address?
With RDBMS
authorized?
Firewall
Simultaneous Data Users
Server-Based RDBMS – “Granules”
• Database Server
• Databases
• Tables
• Records
DB1
DB2
DB3
...
DBn
Site Variable
Date
Value
1 Temperature 8/2/2007 14:00 12.4
1 Temperature 8/2/2007 14:30 12.7
1 Temperature 8/2/2007 15:00 13.1
1
Temperature
8/2/2007 14:00 12.4
Who are the main contenders?
• Commercial software
– Sybase Adaptive Server Enterprise
– IBM DB2
– Oracle
– Microsoft SQL Server
– Teradata
• Free/GPL/Open Source:
– MySQL
– PostgreSQL
MySQL
• No limit on # of CPUs, fully featured, support
for several OSs
• $0 without support, approx. $600-$6000 for
subscription-based support
• Highly scalable, provides support for most
types of indexes and storage methods
Things to Consider When
Deciding on a RDBMS
• Price
• Operating System Support
• Most important features
– ACID (Atomicity, Consistency, Isolation, Durability)
– Referential Integrity support
– Transactions support
• Scalability and security
• Availability of support and software
• Potential longevity
ACID Properties of Database
Transactions
• Atomicity – each transaction is “all or
nothing”
• Consistency – any transaction brings the
database from one valid state to another
• Isolation – concurrent execution of
transactions results in a system state that
would be obtained if they executed serially
• Durability – once a transaction has been
committed, it will remain so
Physical Implementation of a Data
Model within a RDBMS
1.
2.
3.
4.
Create a new database
Create tables for entities
Define attributes and data types
Create relationships and define their
properties
5. Define constraints
All of this can be scripted/automated using SQL
MySQL Workbench
• MySQL Workbench is a powerful graphical DB
management tool
– Create and modify ER diagrams
– Administrate databases (create, modify, backup /
restore DB)
– Create/ view / modify table data and other database
objects
– Write and execute SQL queries
17
Authentication in MySQL
• Performed when you connect to the database server
• Establishes your identity
• Enables you to create accounts for MySQL Server without
giving access to the rest of the server
• “root” = system administrator access
Connecting to a MySQL Server
• Connecting to a MySQL Server requires:
– The name of the server machine or IP address and
port number (3306 is default)
– Username
– Password
DEMO: Connecting to a MySQL Server
Creating a New Database
• In MySQL Workbench, click the “Create new schema” button
• In MySQL, “Schema” = “Database”
Creating a New Database (2)
• In the "New schema" tab enter the name for your new
schema, set the Default Collation, and click “Apply”
Character Set:
A set of symbols
and encodings
Collation: A set
of rules for
comparing
characters in a
set
DEMO: Creating and Deleting
Databases in MySQL
Reduction of an ER Diagram to Tables
• Converting an ER diagram to table format is
the basis for deriving a relational database
– Entities are expressed as tables that contain data
– A database is a collection of tables
– Tables are assigned the same name as the entity
– Each table has columns that correspond to
attributes – each column has a unique name
– Each column must have a single data type
Data Types
• Each attribute of an entity (column in a
database table) must have a single data type
• Data types are enforced by RDBMS software
Table: DataValues
Attribute
Data Type
Sample Data
ValueID
Integer
1
SiteID
Integer
5
VariableID
Integer
5
DateTime
Date/Time
8/15/2013 4:30 PM
DataValue
Double
4.567
Data Types
• Data types can be specific to RDBMS software
RDBMS
Integer
Floating Point
Decimal
String
Date/Time
MS SQL Server
TINYINT,
SMALLINT, INT,
BIGINT
FLOAT, REAL
NUMERIC,
DECIMAL,
SMALLMONEY,
MONEY
CHAR,
VARCHAR,
TEXT, NCHAR,
NVARCHAR,
NTEXT
DATE, DATETIMEOFFSET,
DATETIME2,
SMALLDATETIME,
DATETIME, TIME
MySQL
TINYINT (8-bit),
SMALLINT (16bit), MEDIUMINT
(24-bit), INT (32bit), BIGINT (64bit)
FLOAT (32-bit),
DOUBLE (aka
REAL) (64-bit)
DECIMAL
CHAR,
BINARY,
VARCHAR,
VARBINARY,
TEXT,
TINYTEXT,
MEDIUMTEXT,
LONGTEXT
DATETIME, DATE,
TIMESTAMP, YEAR
PostgreSQL
SMALLINT (16bit), INTEGER (32bit), BIGINT (64bit)
REAL (32-bit),
DOUBLE
PRECISION
(64-bit)
DECIMAL,
NUMERIC
CHAR,
VARCHAR,
TEXT
DATE, TIME (with/without
TIMEZONE), TIMESTAMP
(with/without
TIMEZONE), INTERVAL
Quick summary from: http://en.wikipedia.org/wiki/Comparison_of_relational_database_management_systems
Data Types in MySQL
http://dev.mysql.com/doc/refman/5.7/en/data-types.html
• Numeric
– Integer types: bit, tinyint, smallint, mediumint, int, bigint
– Fixed-point types: decimal, numeric (exact numeric
values to preserve precision)
– Floating-point types: float, double (approximate values)
• Date and Time
– date, datetime, timestamp, time, year
• Strings
– char(size) – fixed length string, right padded
– varchar(size) – variable length string
– tinytext, text, mediumtext, longtext - text data block
Data Types in MySQL (2)
• Binary data
– binary(size) – binary byte strings
– varbinary(size)
– tinyblob, blob, mediumblob, longblob – binary large
object
• Spatial Data Types
– geometry
– point, multipoint
– linestring, multilinestring
– polygon, multipolygon
Data Types in MySQL (3)
• Nullable and NOT NULL types
– All types in SQL Server may or may
not allow NULL values
• Primary key columns
– Define the primary key
• Auto-increment columns
– Automatically increased values when a new row is
inserted (auto-increment values)
– Used in combination with primary key
Creating Tables
• Expand database view in the schemas list
• Right click on “Tables” and select “Create Table”
30
Creating Tables (2)
• Enter table name and define the table columns
(name, data type, and properties):
Enter the name of
Choose the data type of
the column here
the column here
31
Choose properties here
Creating Tables (3)
• Defining column properties
– PK – the column is the primary key for the table
– NN – the column is not nullable
– UQ – Unique Index, the values in the column must be
unique
– BIN – the values in the column are binary
– UN – the values in the column are unsigned
– ZF – Zero fill, integer values will be padded with leading
zeros for display
– AI – the values in the column should be set automatically
using an auto-increment (cannot be assigned manually)
32
Creating Tables (4)
• It is best practice to set the name of the table at the
time it is created
Enter the name of
the table here
33
DEMO: Creating and
Deleting Tables
34
Creating Relationships
• Alter child table to add foreign key attribute
• Alter child table to add foreign key relationship
Create and
name the
relationship
Choose the
referenced
parent table
Match the
primary and
foreign key
attributes
Choose what
to do on
update and
delete
DEMO: Creating Relationships
36
Authorization in MySQL
• Assigning specific permissions to specific users
for specific database objects
DEMO: Creating Database Users
and Assigning Permissions in MySQL
Summary
• Physical database implementation requires
choices about hardware, software, security,
data types, formats and storage, and other
factors
• RDBMS provide the ability to implement a
database in a multi-user, server environment
• MySQL Workbench provides tools for
database creation, editing, and administration
– including forward and reverse engineering