crystal reports 2d barcode RELATIONAL DATABASE MODELING AND DATABASE DESIGN in Font

Generation QR in Font RELATIONAL DATABASE MODELING AND DATABASE DESIGN

CHAPTER 2 RELATIONAL DATABASE MODELING AND DATABASE DESIGN
Print QR Code JIS X 0510 In None
Using Barcode maker for Font Control to generate, create QR image in Font applications.
www.OnBarcode.com
Making Code 3 Of 9 In None
Using Barcode creator for Font Control to generate, create Code 3/9 image in Font applications.
www.OnBarcode.com
The purpose of physical database design is to implement your logical design. Following are some of the key tasks in the physical design stage: Translating the logical database model to fit your specific DBMS Choosing the storage setup with an eye on maximizing efficiency Creating tables (by transforming entities into tables) and the columns for each of the tables Creating primary keys, foreign keys, and constraints (thus formalizing the relationships among the objects)
EAN 128 Maker In None
Using Barcode creation for Font Control to generate, create EAN / UCC - 14 image in Font applications.
www.OnBarcode.com
Data Matrix ECC200 Generation In None
Using Barcode drawer for Font Control to generate, create Data Matrix ECC200 image in Font applications.
www.OnBarcode.com
Transforming Entities and Relationships
Create EAN 13 In None
Using Barcode creation for Font Control to generate, create GTIN - 13 image in Font applications.
www.OnBarcode.com
Generating Barcode In None
Using Barcode encoder for Font Control to generate, create Barcode image in Font applications.
www.OnBarcode.com
In the first stage of the physical design process, you transform the entity-relationship diagrams into relational tables. You create the tables based on the different groups or types of information that you have in the database. For example, you may create a table called People to hold information about the members of an organization, a table called Payments to track membership payments, and so on. What if you want to ensure that the data in your tables is unique, which is a basic assumption in most cases How about establishing relationships among tables that hold related information You can use primary keys and foreign keys to ensure uniqueness and valid relationships in your database. You ll examine these two types of keys in detail in the following sections.
Encode GS1 - 12 In None
Using Barcode generator for Font Control to generate, create UCC - 12 image in Font applications.
www.OnBarcode.com
Make International Standard Book Number In None
Using Barcode maker for Font Control to generate, create ISBN - 13 image in Font applications.
www.OnBarcode.com
Primary Keys
QR-Code Decoder In C#.NET
Using Barcode decoder for VS .NET Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
Drawing QR Code In None
Using Barcode generator for Microsoft Word Control to generate, create QR Code image in Office Word applications.
www.OnBarcode.com
A primary key is a column or a combination of columns that uniquely identifies each record (or row) in a table. In tables that have records for different people, it is common to use social security numbers as primary keys because it s obvious that every person has a unique social security number. If there is no appropriate column you can choose as a primary key, you can use system-generated numbers to uniquely identify your rows. A primary key must be unique and present in every row of the table to maintain the validity of the data. You must select the primary keys from among the list of candidate keys for all the tables in your database. If you are using software to model the data, it is likely that you will already have defined and created all the keys for each entity. The application team determines the best candidates for the primary keys.
Code 128 Code Set B Generation In None
Using Barcode encoder for Office Word Control to generate, create Code 128A image in Microsoft Word applications.
www.OnBarcode.com
Barcode Printer In None
Using Barcode creation for Word Control to generate, create Barcode image in Microsoft Word applications.
www.OnBarcode.com
Foreign Keys
Data Matrix 2d Barcode Scanner In .NET Framework
Using Barcode recognizer for .NET framework Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
Recognizing UPC A In Java
Using Barcode scanner for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
Suppose you have two tables, Employees and Departments, with the simple requirement that every employee must be a member of a department. The way to ensure this is to check that all employees have a Department column in the Employees table. Let s say the Departments table has a primary key named Department ID you need to have this primary key column in the Employees table. Remember that the Employees table will have its own primary key, such as SSN. However, the values of the Department ID column in the Employees table must all be present in the Departments table. This Department ID column in the Employees table is the primary key in the Departments table, and you refer to it as a foreign key in the Employees table. Foreign keys ensure that only valid data is entered in your tables.
Decode QR-Code In C#
Using Barcode decoder for .NET Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
Draw QR Code 2d Barcode In Visual Basic .NET
Using Barcode creator for Visual Studio .NET Control to generate, create QR Code image in Visual Studio .NET applications.
www.OnBarcode.com
Designing Different Types of Tables
Barcode Creator In Visual Studio .NET
Using Barcode maker for ASP.NET Control to generate, create Barcode image in ASP.NET applications.
www.OnBarcode.com
Make Barcode In Java
Using Barcode creation for BIRT reports Control to generate, create Barcode image in BIRT applications.
www.OnBarcode.com
You should determine which of your tables are going to be your main data tables and which will be your lookup tables. A lookup table generally contains static data, such as the Departments table
Printing Code 128C In Java
Using Barcode drawer for Java Control to generate, create Code128 image in Java applications.
www.OnBarcode.com
Draw USS Code 39 In Java
Using Barcode printer for BIRT Control to generate, create Code 39 Full ASCII image in Eclipse BIRT applications.
www.OnBarcode.com
CHAPTER 2 RELATIONAL DATABASE MODELING AND DATABASE DESIGN
discussed in the previous section. Usually when you have a foreign key in a table, the table from which the foreign key comes will be your lookup table. One of the ways to ensure good performance later on is to spend a lot of time at the design stage thinking about how your users are going to use the database. For example, whereas normalization may be a technically correct way to design a database, it may require reading more tables for a single query. The more tables you need to join for any query, the higher the CPU and memory usage, which may hurt database performance. If you perform the appropriate amount of due diligence at the design stage, you can depict your organization s process flow accurately while you design your tables. When you consider the cost and frustration involved in tuning poorly written SQL later on, it s clear that it s worth putting some effort into carefully designing tables and fields.
Copyright © OnBarcode.com . All rights reserved.