1. Overview of Data Access
MIS Professor Sandvig
9/22/2018
Overview of Data Access
MIS 324
Professor Sandvig

2. MIS 324 -- Professor Sandvig
9/22/2018
Overview
ADO.NET overview
Data Access
Displaying data

3. MIS 324 -- Professor Sandvig
9/22/2018
ADO.NET Overview
“Any web application worth writing involves data access.” Stephen Walther
ADO
ActiveX Data Objects
Microsoft’s data access technologies
Set of classes that provide data access services
Class Library System.Data

4. MIS 324 -- Professor Sandvig
9/22/2018
ADO.NET Overview
Support for most relational databases
Sql Server
Oracle
MySql
Any ODBC compliant database
Open Database Connectivity standard

5. MIS 324 -- Professor Sandvig
9/22/2018
.NET Data options
Programmatically
Use connection & command objects
Pass SQL to database
Very flexible approach
Similar to PHP
Entity Framework
VS examines database
Creates classes representing database structure
Query with LINQ (language integrated query)
Intellisense support
Added to .NET 3.5
Proprietary Microsoft product

6. MIS 324 -- Professor Sandvig
9/22/2018
Retrieving Data
MIS 324
Will use programmatic approach
Benefits
Flexible
Uses SQL
Standard OOP programming techniques
MIS 424
Entity Framework
Fast & convenient

7. MVC Approach Separation of duties: Model DataRepository class
Describes application data
DataRepository class
Sql statements and data access classes
Controller
Handles requests
View
Displays data and forms

8. Repository All data access logic Goal: Loose coupling Sql statements
Database classes
Connection
Etc.
Goal: Loose coupling
Different data source affects only repository

9. ORM – Object Relation Mapper
Maps model to sql parameters
Query results to model

10. ORM We use Dapper ORM Developed by StackOverflow “King of ORMs”
For its site
“King of ORMs”

11. ORM //Get one employee with Dapper
public CrudModel GetOneEmployee(int id) {
using (IDbConnection db = connection)
string sql = "select Id, Fname, Lname from
EmployeeDetails where id
CrudModel employee = db.Query<CrudModel>(sql, new
{ id }).SingleOrDefault();
return employee; }
//Get one employee without Dapper public CrudModel GetOneEmployeeNoDapper(int id) { //each sql parameter must be added as a parameter //each return value must be assigned to data object string sql = "select Id, Fname, Lname from EmployeeDetails where id SqlDataReader reader; using (SqlCommand command = new SqlCommand(sql)) //add input parameters. SqlParameter parm = new id); command.Parameters.Add(parm); //execute reader = command.ExecuteReader(); } //create data object and assign values from reader CrudModel employee = new CrudModel(); while (reader.Read()) employee.Id = Convert.ToInt32(reader["id"]); employee.Fname = Convert.ToString(reader["Fname"]); employee.Lname = Convert.ToString(reader["Lname"]); }; return employee;

12. Retrieving Data .NET MVC
MIS Professor Sandvig
9/22/2018
Retrieving Data .NET MVC
Steps:
Model
Database (Sql Server)
DataRepository
Controller
Views

13. MIS 324 -- Professor Sandvig
9/22/2018
Example – Repository
See handout: Read Database
Output

14. MIS 324 -- Professor Sandvig
9/22/2018
Summary
ADO.NET
Classes that handle data access
Provides consistent programming interface to data sources
MVC
Database access handled in DataRepository
Controller calls repository methods
Next: SQL Server Express
Creating databases & using with ASP.NET