Chapter 6 Working with Data in a Connected Environment

1 VB.Net 2005 - Chapter 6 1 Chapter 6 Working with Data in a Connected Environment VB.Net 2005 - Chapter 6 2 Chapter 6  Lesson 0: Connected & Disconnectd Environment in ADO.NET  Lesson 1: Creating and Executing Command Objects  Lesson 2: Working with Parameters in SQL Commands Note: Lesson 3: BLOBs and Lesson 4: Bulk Copy: For reading at home Lesson 5: Performing Transactions by Using the Transaction Object 2 VB.Net 2005 - Chapter 6 3 Lesson 0: Connected & Disconnectd Environment in ADO.NET  2 ways using with ADO.NET Connection Data Adapter Data Source DataSet Web Form Windows Form Connection Command Data Source DataReader Web Form Windows Form Disconnectd Connected VB.Net 2005 - Chapter 6 4 Disconnected Data Access  Single database server can support many users  reduced server's resources  Data using more flexible  Data not 'tied' to a connection  easy to pass between tiers or persist to file  Highly suited to Web and n-tier Apps  Expensive when open, close connections  Retrieving large result sets can be very slow  Places demand on client memory and CPU Advantages Disadvantages 3 VB.Net 2005 - Chapter 6 5 System.Data Architecture DataReader Database Program DataProvider DataSet DataAdapter VB.Net 2005 - Chapter 6 6 Details: System.Data Architecture Command Object Connection Object Program Provider DataSet DataReader DataAdapter Database Action SQL Maintain data Maintain data Get data Get data 4 VB.Net 2005 - Chapter 6 7 Main Difference:DataSet-DataReader DataSet  Data structure to store schema and data in a disconnected fashion  Useful for editing data offline and later update to data source  DataReader  Like Phone connection.  Doesn’t need to store data in memory  Object to access data in a connected, forward-only, read- only fashion  When performance is your chief concern, especially with large amounts of data, use a DataReader class VB.Net 2005 - Chapter 6 8 Differences DataSet and DataReader 5 VB.Net 2005 - Chapter 6 9 Lesson 1: Creating and Executing Command Objects  1.What Are Command Objects?  2.Creating and Configuring Command Objects  3.Creating SQL Commands (SQL Statements) with the Query Designer VB.Net 2005 - Chapter 6 10 Lesson 1: Creating and Executing Command Objects  1.What Are Command Objects? 6 VB.Net 2005 - Chapter 6 11 Lesson 1: Creating and Executing Command Objects  1.What Are Command Objects?  To execute SQL statements,stored procedures  Contain the necessary information to execute SQL statements VB.Net 2005 - Chapter 6 12 Lesson 1: Creating and Executing Command Objects  1.What Are Command Objects?  Depend on Data Providers 7 VB.Net 2005 - Chapter 6 13 Lesson 1: Creating and Executing Command Objects  1.What Are Command Objects?  Common properties (p.254)  CommandText  SQL string, table name, proc name  CommandType  Text  Proc  Table  Connection  Parameters VB.Net 2005 - Chapter 6 14 Lesson 1: Creating and Executing Command Objects  1.What Are Command Objects?  Common Command Object Methods (p.255)  ExecuteNonQuery  ExecuteReader  ExecuteScalar 8 VB.Net 2005 - Chapter 6 15 Lesson 1: Creating and Executing Command Objects  2.Creating and Configuring Command Objects  Creating a Command Object That Executes a SQL Statement  Creating a Command Object That Executes a Stored Procedure  Creating a Command Object That Performs Catalog Operations  Creating a Command Object That Returns a Single Value VB.Net 2005 - Chapter 6 16 Lesson 1: Creating and Executing Command Objects  2.Creating and Configuring Command Objects  Creating a Command Object That Executes a SQL Statement (p.256) 9 VB.Net 2005 - Chapter 6 17 Lesson 1: Creating and Executing Command Objects  2.Creating and Configuring Command Objects  Creating a Command Object That Executes a Stored Procedure (p.257) VB.Net 2005 - Chapter 6 18 Lesson 1: Creating and Executing Command Objects  2.Creating and Configuring Command Objects  Creating a Command Object That Performs Catalog Operations (p.257) 10 VB.Net 2005 - Chapter 6 19 Lesson 1: Creating and Executing Command Objects  2.Creating and Configuring Command Objects  Creating a Command Object That Returns a Single Value (p.258) VB.Net 2005 - Chapter 6 20 Lesson 1: Creating and Executing Command Objects  3.Creating SQL Commands (SQL Statements) with the Query Designer  Creating SQL Commands (SQL Statements) with the Query Designer  Performing Database Operations Using Command Objects [...]... of Parameters 3.Creating Parameters 4.Adding Parameters to Command Objects VB.Net 2005 - Chapter 6 32 16 Lesson 2: Working with Parameters in SQL Commands 1.What Is a Parameter and Why Should I Use Them? parameter can be thought of as a type of variable use to pass and return values between your application and a database Parameter data types are assigned using the types defined in the System .Data. SqlDbType... SQL Commands (SQL Statements) with the Query Designer Performing Database Operations Using Command Objects (p 260 ) VB.Net 2005 - Chapter 6 22 11 How to receive DataReader Connectionn Connectionn Open Commandn Commandn Which data? DataReadern DataReadern Result 23 VB.Net 2005 - Chapter 6 DataReader Class Datareader and MS Access Store the information obtained by the command In stateless stream type... Working with Parameters in SQL Commands 4.Adding Parameters to Command Objects Command objects have a Parameters property that represents a collection of parameters After you create a parameter, you must add it to the Parameters collection of the Command object VB.Net 2005 - Chapter 6 36 18 Lesson 2: Working with Parameters in SQL Commands Lab: Lab: Working with Parameters page 275 VB.Net 2005 - Chapter. .. Create MA access database Table Student(ID,FirstName,Lastname,Phone) Using Client dynamic SQL to put data in Listview Using Client dynamic SQL to detail data to Textboxes Exit VB.Net 2005 - Chapter 6 44 22 Ex Insert new record Exit Save VB.Net 2005 - Chapter 6 45 Access Insert into sv(ma,lname,fname,phone) Values (?,?,?,?) Cmd.parameters.add(p1) Cmd.parameters.add(p2) Cmd.parameters.add(p3) Cmd.parameters.add(p4)... the garbage collector-> explicitly close Tie the connection ‘ life to DataReader CommandBehavior.CloseConnection in ExecuteReader VB.Net 2005 - Chapter 6 28 14 Note about DataReader The first row of data is not available until you call the Read method Using with stored procedure uses a return or output parameter, must close DataReader before get parameter DataReader cannot be used for data binding System.DBNull.value... MessageBox.Show(drSinhVien.GetString(0)) Loop drSinhVien.Close() conSinhVien.Close() VB.Net 2005 - Chapter 6 27 Note: DataReader ADO.NET does not provide all the server-side cursor Don’t keep DataReaders open longer than necessary For flexible updates & client-side manipulation… Use DataSets and DataAdapters Only one DataReader use at a time Tie to Connection=> cannot used other DataReader To reuse connection=>call DataReader.Close... designated in the Direction property of the parameter With a parameter, we ou can set its Direction property to Input, Output, InputOutput, or ReturnValue VB.Net 2005 - Chapter 6 34 17 Lesson 2: Working with Parameters in SQL Commands 3.Creating Parameters (p 274) Create parameters:instance of the Parameter class setting its name and data type Choose ParameterDirection VB.Net 2005 - Chapter 6 35 Lesson 2: Working. .. enumeration pass parameter values to SQL statements when we want to change the criteria of your queries quickly VB.Net 2005 - Chapter 6 33 Lesson 2: Working with Parameters in SQL Commands 2.Types of Parameters (p 274) Input parameter (default) Output parameter InputOutput parameter InputOutput parameters are used to both send and receive data when executing a command The type of parameter is designated... sdr.GetString(0) sb.Append(strProductName) sb.Append(sdr.GetDecimal(1).ToString()) sb.Append(vbTab) sb.Append(sdr.GetInt 16( 2).ToString()) End While VB.Net 2005 - Chapter 6 30 15 Lesson 1: Creating and Executing Command Objects 3.Creating SQL Commands (SQL Statements) with the Query Designer Lab: P 265 VB.Net 2005 - Chapter 6 31 Lesson 2: Working with Parameters in SQL Commands 1.What Is a Parameter and Why... Cmd.parameters.add(p4) Insert into sv(ma,lname,fname,phone) Values (@ma,@lname,@fname,@phone) insert into sv(ma,[last name],[first name],phone) values (?,?,?,?) VB.Net 2005 - Chapter 6 46 23 Exer 2 Copy Exer 1 to new folder Change the way to get data Client Dynamic SQL -> Client Parameters SQL VB.Net 2005 - Chapter 6 47 Exer 3 Copy Exer 2 to new folder Change the way to get data Client Parameters SQL ->server Parameters . 1 VB.Net 2005 - Chapter 6 1 Chapter 6 Working with Data in a Connected Environment VB.Net 2005 - Chapter 6 2 Chapter 6  Lesson 0: Connected & Disconnectd Environment. CPU Advantages Disadvantages 3 VB.Net 2005 - Chapter 6 5 System.Data Architecture DataReader Database Program DataProvider DataSet DataAdapter VB.Net 2005 - Chapter 6 6 Details: System.Data Architecture Command. with the Query Designer VB.Net 2005 - Chapter 6 10 Lesson 1: Creating and Executing Command Objects  1.What Are Command Objects? 6 VB.Net 2005 - Chapter 6 11 Lesson 1: Creating and Executing