c# .net barcode generator free ActiveRecord: A Sneak Peek in Font

Maker Data Matrix in Font ActiveRecord: A Sneak Peek

ActiveRecord: A Sneak Peek
Data Matrix ECC200 Generator In None
Using Barcode maker for Font Control to generate, create ECC200 image in Font applications.
www.OnBarcode.com
Printing Code 128 Code Set A In None
Using Barcode creator for Font Control to generate, create Code 128A image in Font applications.
www.OnBarcode.com
So far in this chapter you ve worked directly with databases using a whole new language: SQL. Working with a database in this way is more efficient and reliable than putting data into text files, as you did earlier, but ActiveRecord makes it easier still. ActiveRecord is a product of the Ruby on Rails framework, which we ll be covering in 13, but can be used entirely independently of it. ActiveRecord will be covered in more depth in that chapter, but deserves a brief summary here. ActiveRecord abstracts away all the details of SQL and database design and makes it possible to relate to items within databases in an object-oriented fashion, as you did with PStore. ActiveRecord gives you objects that correspond to rows and classes that correspond to tables, and you can work with the data using Ruby syntax, like so:
Paint EAN / UCC - 13 In None
Using Barcode generation for Font Control to generate, create European Article Number 13 image in Font applications.
www.OnBarcode.com
Create Data Matrix ECC200 In None
Using Barcode drawer for Font Control to generate, create DataMatrix image in Font applications.
www.OnBarcode.com
person = Person.find(:first, :conditions => ["name = ", "Chris"]) person.age = 50 person.save
Barcode Printer In None
Using Barcode generation for Font Control to generate, create Barcode image in Font applications.
www.OnBarcode.com
PDF 417 Creation In None
Using Barcode generation for Font Control to generate, create PDF417 image in Font applications.
www.OnBarcode.com
This code looks through the people table for a row whose name column matches Chris, and puts an object relating to that row into person. ActiveRecord makes attributes available for all that row s columns, so changing the age column is as easy as assigning to the object s attribute. However, once the object s value has been changed, you issue the save method to save the changes back to the database.
Barcode Creation In None
Using Barcode generator for Font Control to generate, create Barcode image in Font applications.
www.OnBarcode.com
Printing USD8 In None
Using Barcode generator for Font Control to generate, create Code11 image in Font applications.
www.OnBarcode.com
Note The pluralization from a Person class to a people table is an automatic part of ActiveRecord s
Data Matrix Decoder In None
Using Barcode scanner for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
Recognizing DataMatrix In Java
Using Barcode recognizer for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
functionality.
DataMatrix Maker In None
Using Barcode drawer for Office Word Control to generate, create ECC200 image in Microsoft Word applications.
www.OnBarcode.com
Making PDF417 In Java
Using Barcode generation for BIRT Control to generate, create PDF-417 2d barcode image in Eclipse BIRT applications.
www.OnBarcode.com
CHAPTER 9 FILES AND DATABASES
EAN / UCC - 13 Generation In Java
Using Barcode encoder for Android Control to generate, create EAN-13 image in Android applications.
www.OnBarcode.com
Generate Barcode In Visual Studio .NET
Using Barcode maker for .NET Control to generate, create Barcode image in .NET applications.
www.OnBarcode.com
The previous code could replace SQL such as this:
Scanning PDF-417 2d Barcode In C#
Using Barcode decoder for Visual Studio .NET Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
Drawing UCC.EAN - 128 In None
Using Barcode printer for Software Control to generate, create GS1 128 image in Software applications.
www.OnBarcode.com
SELECT * FROM people WHERE name = "Chris" UPDATE people SET age = 50 WHERE name = "Chris"
Barcode Generation In .NET Framework
Using Barcode printer for ASP.NET Control to generate, create Barcode image in ASP.NET applications.
www.OnBarcode.com
Generate QR Code 2d Barcode In VB.NET
Using Barcode generation for .NET framework Control to generate, create QR Code ISO/IEC18004 image in .NET applications.
www.OnBarcode.com
Even SQL gurus familiar with Ruby tend to find Ruby s syntax more natural, particularly in the scope of a Ruby program. There s no need to mix two different languages in one program if both sets of features can be provided in Ruby alone. ActiveRecord will be covered in detail in 13.
Barcode Generation In Java
Using Barcode generation for Java Control to generate, create Barcode image in Java applications.
www.OnBarcode.com
Print QR Code In Java
Using Barcode printer for Java Control to generate, create QR Code image in Java applications.
www.OnBarcode.com
Note ActiveRecord is not the only library to offer features that relate objects to database tables. Og and
Lafcadio (http://lafcadio.rubyforge.org/) are two alternatives, though they re far less popular than ActiveRecord.
Summary
In this chapter we ve looked at how data can flow into and out of your Ruby programs. Initially we looked at the low-level concept of I/O streams before quickly moving on to the pragmatism of databases. Databases provide a way to work with data in a more abstracted fashion without worrying about the underlying structure of the data on the computer s filesystem. Indeed, databases can be located within memory or on totally different machines, and our code could remain the same. Let s reflect on the main concepts covered in this chapter: I/O: Input/Output. The concept of receiving input and sending output by various means on a computer, often via I/O streams. I/O stream: A channel along which data can be sent and/or received. Standard input (stdin): A stream that relates to the default way of accepting data into the application, usually the keyboard. Standard output (stdout): A stream that relates to the default way of outputting data from the application, usually to the screen. File pointer: An abstract reference to the current location within a file. Database: An organized collection of data structured in a way that makes it easy to be accessed programmatically.
CHAPTER 9 FILES AND DATABASES
CSV: Comma-Separated Values. A way of structuring data with attributes separated with commas. CSV can be stored in plain text files. Marshalling: The process of converting a live data structure or object into a flat set of data that can be stored on disk, sent across a network, and then can be used to reconstruct the original data structure or object elsewhere or at some other time. Table: A collection of data organized into rows, with multiple columns, where each column represents a different attribute of each row. There are usually multiple tables within a database, containing different types of data. SQLite: An open source, public-domain relational database API and library that works on a single-user basis on a local machine. It supports SQL as its querying language. MySQL: An open source relational database system available in both community and professional editions. It is maintained by MySQL AB. Web hosting companies commonly offer MySQL database support. PostgreSQL: A free, open source relational database system licensed under the BSD license, making it possible to repackage and sell within commercial products. PostgreSQL is often considered to be of higher performance and have better conformity to SQL standards than MySQL, although it s less commonly used. Oracle: A commercial relational database system developed by Oracle Corp. It s generally used by large businesses for managing extremely large datasets. Primary key: A column (or multiple columns) on a table whose data uniquely identifies each row. DBI: DataBase Interface. A database-agnostic library that makes it easy to communicate between Ruby and database systems. SQL: Structured Query Language. A language specifically designed to create, amend, retrieve, and otherwise manipulate data in relational database systems. ActiveRecord: A library that abstracts databases, rows, columns, and SQL into standard Ruby syntax using classes and objects. It s a major part of the Ruby on Rails framework, which is covered in detail in 13.
Copyright © OnBarcode.com . All rights reserved.