database communication in c# using 3 layer architecture

Database Communica/on in Visual Studio/C#

using 3-‐/er Arcitecture

Hans-‐Pe=er Halvorsen, M.Sc.

The examples uses ADO.NET

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The database-‐centric style. Typically, the clients communicate directly with the database.

A three-‐/er style, in which clients do not connect directly to the database.

Web Services, etc.

3-‐/er/layer Architecture

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Presenta/on Tier

Business Logic Tier

Data Access Tier

Data Source

PL

BL

DAL

Note! The

differen

t layers c

an be on

the

same compu

ter (Logic Layers) o

r on diffe

rent

Compu

ters in a network (Physic

al Layers)

Data Tier -‐ DL

Logic Tier

Why 3-‐Tier (N-‐Tier Architecture?) •  Flexible applica/ons •  Reusable code –  Code once, use many /mes

•  Modularized –  You need only to change part of the code –  You can deploy only one part –  You can Test only one part – Mul/ple Developers

•  Different parts (Tiers) can be stored on different computers

•  Different PlaYorms and Languages can be used •  etc.

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5 h=p://en.wikipedia.org/wiki/Mul//er_architecture

3-‐/er/layer Architecture Presenta4on Tier •  This is the topmost level of the applica/on. •  The presenta/on /er displays informa/on related to such services as browsing

merchandise, purchasing and shopping cart contents. •  It communicates with other /ers by which it puts out the results to the

browser/client /er and all other /ers in the network. •  In simple terms it is a layer which users can access directly such as a web page,

or an opera/ng systems GUI Applica4on 4er (business logic, logic 4er, data access 4er, or middle 4er) •  The logical /er is pulled out from the presenta/on /er and, as its own layer. •  It controls an applica/on’s func/onality by performing detailed processing. Data 4er •  This /er consists of database servers. Here informa/on is stored and retrieved. •  This /er keeps data neutral and independent from applica/on servers or

business logic. •  Giving data its own /er also improves scalability and performance.

6 h=p://en.wikipedia.org/wiki/Mul//er_architecture

3-‐/er Architecture

Presenta/on Tier

Business Logic Tier

Data Access Tier

Database

Presenta/on Tier Presenta/on Tier

Stored Procedures

Different Devices can share the same Business and Data Access Code

The different Tiers can be physical or logical Data Tier

Logic Tier

Web Server

3-‐/er + WebService Architecture -‐ Example

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Presenta/on Tier

Business/Data Logic

Tier

Data Source

Web Services

Team

Fou

nda/

on Server

TFS Cient

Installed on one or more Windows Servers in your LAN or in the Cloud

Data Tier

Stored Procedures

Team Founda/on Server

3-‐/er Architecture Scenarios

Presenta/on Layer

Business Logic

Data Access Logic Database

Presenta/on Layer Presenta/on Layer

Stored Procedures

Client

Client Client

Web Server

Web Service

Presenta/on Layer

Client

Presenta/on Layer

Internet

Local Network (LAN)

Client

Firewall

Presenta/on Layer

Server Server

Crea/ng the Data Tier


Data Tier We are going to create the Database / Data Layer/Tier, including: 1.  Tables 2.  Views 3.  Stored Procedures 4.  Triggers 5.  Script for some “Dummy” Data

Download Zip Files with Tables, Views, Stored Procedures and Triggerse in order to create the Data Tier in SQL Server (The ZIP File is located on the same place as this File)

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Note! Install them in this order

Data Tier

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Tables

Views

Stored Procedures

SQL Server

Triggers

Data Tier

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Database Tables

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Execute the different Scripts inside SQL Server Management Studio

15 You are finished with the Exercise

Crea/ng the Logic Tier


Logic Tier

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Database

Presenta/on Tier

Logic Tier

ASP.NET Web Forms

Data Tier

Presenta/on Tier Presenta/on Tier

WinForms Windows Store App

Purpose: •  All the Apps should/could

share the same Logic Tier •  To make your Apps easier

to maintain and extend •  etc.

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Create an Empty (Blank) Solu4on in Visual Studio

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Add Project for Logic Tier (Data Access)

Select a “Class Library” Project

“LogicTier”

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Add a New Class to the Project (“StudentData.cs”)

“StudentData.cs”

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Create the Code, e.g., like this (“StudentData.cs”):

Create your own Namespace

Improvements: Use Try... Catch ...

A View that collects data from several tables

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You should test the SQL Query in the SQL Server Management Studio first

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Code (“StudentData.cs”): using System.Data.SqlClient; using System.Data.SqlTypes; using System.Data; namespace Tuc.School.LogicTier { public class StudentData { public DataSet GetStudentDB(string connectionString) { string selectSQL = "select StudentName, StudentNumber, SchoolName, ClassName,

Grade from StudentData order by StudentName"; // Define the ADO.NET objects. SqlConnection con = new SqlConnection(connectionString); SqlDataAdapter da = new SqlDataAdapter(selectSQL, con); DataSet ds = new DataSet(); da.Fill(ds); return ds; } } }

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Create a proper name for the Assembly (.dll File)

This will be the Assembly for your Logic Tier, that can be imported and used in other projects. Create once – use it many /mes!!

Then Build your Project (hopefully with no errors)

Right-‐click on the Project in the Solu/on Explorer and select Proper/es

Crea/ng the Presenta/on Tier


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Presenta/on Layer Desktop App: WinForms

We assume the App will be used only in the local LAN (or local on the same computer where the database is located) and that we have direct access to the Database)

Label

DataGridView

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Add a WinForm Project

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Add a New Class (“StudentWinForm.cs”)

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Add Code in Class

Add a Reference to the Assembly in the Logic Tier

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Code for Class “StudentWinForm.cs”

using System.Data; using Tuc.School.LogicTier; namespace Tuc.School.WinFormApp { class StudentWinForm { public DataSet GetStudent(string connectionString) { StudentData studentData = new StudentData(); return studentData.GetStudentDB(connectionString); } } }

Reference to our Logic Tier

Since we are using the DataSet Class

Our Database Method in our Logic Tier

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Create Form

Label

DataGridView

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Create Form Code

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using System.Configuration; using Tuc.School.WinFormApp; namespace WinFormApp { public partial class Form1 : Form { private string connectionString =

ConfigurationManager.ConnectionStrings["SCHOOLConnectionString"].ConnectionString; public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { FillStudentGrid(); } private void FillStudentGrid() { DataSet ds = new DataSet(); StudentWinForm studentList = new StudentWinForm(); ds = studentList.GetStudent(connectionString); dataGridViewStudentInformation.DataSource = ds.Tables[0]; } } }

WinForm Code Note!

Connec/onString is stored in App.config

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Note! Add System.Configura/on Reference

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Create DB Connec/onString in App.config <?xml version="1.0" encoding="utf-‐8" ?> <configuration> <startup> <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" /> </startup> <connectionStrings> <add name="SCHOOLConnectionString" connectionString="Data Source=macwin8;Initial Catalog=SCHOOL;Persist Security Info=True;User ID=sa;Password=xxxxxx" providerName="System.Data.SqlClient" /> </connectionStrings> </configuration>

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Test it

It works!!!

Recommended Li=erature

•  Tutorial: Introduc/on to Database Systems h=p://home.hit.no/~hansha/?tutorial=database

•  Tutorial: Structured Query Language (SQL) h=p://home.hit.no/~hansha/?tutorial=sql

•  Tutorial: Using SQL Server in C# •  Tutorial: Introduc/on to Visual Studio and C# h=p://home.hit.no/~hansha/?tutorial=csharp

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Hans-‐PeUer Halvorsen, M.Sc. Telemark University College Faculty of Technology Department of Electrical Engineering, Informa4on Technology and Cyberne4cs

E-‐mail: [email protected] Blog: hUp://home.hit.no/~hansha/

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database communication in c# using 3 layer architecture

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