how to print barcode in c# windows application THE RELATIONAL MODEL: DATA RELATIONS in Font

Creator PDF 417 in Font THE RELATIONAL MODEL: DATA RELATIONS

THE RELATIONAL MODEL: DATA RELATIONS
Painting PDF 417 In None
Using Barcode maker for Font Control to generate, create PDF-417 2d barcode image in Font applications.
www.OnBarcode.com
Generate UPC-A In None
Using Barcode maker for Font Control to generate, create UCC - 12 image in Font applications.
www.OnBarcode.com
A relational database table is essentially a two-dimensional matrix with rows (records) and columns (fields). A primary key is a column that uniquely identifies each row, and that means you cannot store the same value in a primary key column of any two records (so it is also a unique key). The primary key is usually a single numeric column, but it can also be composed as a set of columns, in which case it is called a composite primary key. Tables can be linked or related to one another using relationships. To set up a relationship, you need foreign keys, which are columns that store primary key values in a host table. For instance, in a one-to-one relationship, a record in table A can be associated with a record in table B by A containing a foreign key to B s primary key column, or vice versa, or both, depending on the navigability of the relationship. A one-to-one relationship is rare because it makes more sense to merge the two tables, unless the foreign key is allowed to be null. On the other hand, one-to-many (1..*) relationships are ubiquitous, allowing records in table A to be associated with multiple records in table B. For instance, a Customers table is likely to be associated with an Orders table this way, allowing each customer to have multiple orders. This can be modeled by storing a foreign key in Orders that refers to a Customers primary key. By moving two (or more) foreign keys in a separate so-called association table, we obtain a many-to-many relationship between those tables. Referential integrity refers to the fact that only valid primary key values are allowed in a foreign key column.
Printing Code128 In None
Using Barcode creation for Font Control to generate, create Code 128 Code Set A image in Font applications.
www.OnBarcode.com
Code39 Maker In None
Using Barcode maker for Font Control to generate, create Code 39 Extended image in Font applications.
www.OnBarcode.com
CHAPTER 15 WORKING WITH DATA
Generating Barcode In None
Using Barcode creator for Font Control to generate, create Barcode image in Font applications.
www.OnBarcode.com
Creating PDF417 In None
Using Barcode maker for Font Control to generate, create PDF-417 2d barcode image in Font applications.
www.OnBarcode.com
Choosing Your Database Engine
Barcode Encoder In None
Using Barcode creator for Font Control to generate, create Barcode image in Font applications.
www.OnBarcode.com
Creating ANSI/AIM ITF 25 In None
Using Barcode encoder for Font Control to generate, create ANSI/AIM I-2/5 image in Font applications.
www.OnBarcode.com
Table 16-1 shows some of the most common database engines, all of which can be used from F# and .NET.
Drawing PDF 417 In None
Using Barcode generation for Software Control to generate, create PDF417 image in Software applications.
www.OnBarcode.com
PDF-417 2d Barcode Creator In None
Using Barcode generation for Microsoft Excel Control to generate, create PDF-417 2d barcode image in Excel applications.
www.OnBarcode.com
Table 16-1. Common Databases
Making Data Matrix In Visual Studio .NET
Using Barcode drawer for ASP.NET Control to generate, create Data Matrix image in ASP.NET applications.
www.OnBarcode.com
UPC A Maker In None
Using Barcode generator for Microsoft Word Control to generate, create Universal Product Code version A image in Word applications.
www.OnBarcode.com
Name
Data Matrix 2d Barcode Printer In Java
Using Barcode creator for Java Control to generate, create Data Matrix image in Java applications.
www.OnBarcode.com
Data Matrix 2d Barcode Generator In None
Using Barcode drawer for Office Excel Control to generate, create Data Matrix 2d barcode image in Office Excel applications.
www.OnBarcode.com
PostgreSQL SQLite
Make UPC Symbol In Java
Using Barcode generation for Eclipse BIRT Control to generate, create GTIN - 12 image in BIRT applications.
www.OnBarcode.com
European Article Number 13 Encoder In None
Using Barcode creation for Word Control to generate, create GS1 - 13 image in Word applications.
www.OnBarcode.com
Type
Draw Barcode In None
Using Barcode generator for Word Control to generate, create Barcode image in Microsoft Word applications.
www.OnBarcode.com
Creating EAN-13 In None
Using Barcode encoder for Microsoft Excel Control to generate, create EAN 13 image in Excel applications.
www.OnBarcode.com
Open source Open source
Creating European Article Number 13 In Java
Using Barcode generator for Java Control to generate, create EAN13 image in Java applications.
www.OnBarcode.com
Recognizing ANSI/AIM Code 39 In None
Using Barcode scanner for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
Description
Open source database engine Small, embeddable, zero-configuration SQL database engine Based on Borland Interbase Reliable and popular database Reliable database engine One of the most popular enterprise database engines Microsoft s main database engine Free and easy-to-use version of SQL Server Mobile database engine
Available from
http://postgresql.org/ http://www.sqlite.org/
Firebird MySQL Mimer SQL Oracle SQL Server SQL Server Express Sybase iAnywhere
Open source Open source Commercial Commercial Commercial Commercial Commercial
http://www.firebirdsql.org/ http://www.mysql.com/ http://www.mimer.com/ http://www.oracle.com/ http://www.microsoft.com/sql/ default.mspx http://www.microsoft.com/sql/ editions/express/default.mspx http://www.ianywhere.com/
Applications communicate with relational databases using Structured Query Language (SQL). Each time you create tables, create relationships, insert new records, or update or delete existing ones, you are explicitly or implicitly issuing SQL statements to the database. The examples in this chapter use a dialect of Standard SQL, called Transact-SQL (T-SQL), used by SQL Server and SQL Server Express. SQL has syntax to define the structure of a database schema (loosely speaking, a collection of data tables and their relations) and also syntax to manage the data within. These subsets of SQL are called Data Definition Language (DDL) and Data Manipulation Language (DML), respectively. The most important DDL statements are the following: CREATE/ALTER/DROP TABLE CREATE/DROP VIEW
Understanding ADO.NET
ADO.NET is the central database access machinery in the .NET Framework, and it provides full XML support, disconnected and typed datasets, scalability, and high performance. In this section, we give a brief overview of the ADO.NET fundamentals.
C HA PTER 15 WO RK ING WI T H D A TA
With ADO.NET, data is acquired through a connection to the database via a provider. This connection serves as a medium to execute a command against; this can be used to fetch, update, insert, or delete data from the data store. Statements and queries are articulated as SQL text (CREATE, SELECT, UPDATE, INSERT, and DELETE statements) and are passed to the command object s constructor. When you execute these statements, you obtain data (in the case of queries) or the number of affected rows (in the case of UPDATE, INSERT, or DELETE statements). The data returned can be processed via two main mechanisms: sequentially in a read-only fashion using a DataReader object or by loading it into an in-memory representation (a DataSet object) for further disconnected processing. DataSet objects store data in a set of table objects and along with them metadata that describes their relationships and constraints in a fully contained model. ADO.NET 2.0 comes with four data providers: SQLClient, OleDb, Oracle, and Odbc. Table 16-2 describes them and a couple of more commonly used providers. These providers act as the main gateway to the database.
Copyright © OnBarcode.com . All rights reserved.