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Captulo 8

COM

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Objetivo

Crear una biblioteca de clases que

permita acceder a una base de datos.

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Imports

Imports System

Imports System.Data

Imports System.Data.SqlClient Imports System.Text

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Declaracin de variables

Namespace SQLNameSpace

Public Class SQLClass

Private ls_sql as string Private ls_ConnStr as string

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Constructor

Public Sub New()

MyBase.New()

ls_sql = ""ls_ConnStr = ""

End Sub

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Propiedades

Public Property SQL as string

Get

Return ls_sql

End Get

Set

ls_sql = valueEnd Set

End Property

Public Property ConnStr as string

Get

Return ls_ConnStr

End GetSet

ls_ConnStr = value

End Set

End Property

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Mtodo Populate

Public Function Populate() As DataView

Dim myConnection As SqlConnection

Dim myCommand As SqlDataAdapter

Dim ds As New DataSetmyConnection = New SqlConnection(ConnStr)

myCommand = New SqlDataAdapter(SQL,myConnection)

myCommand.Fill(ds, "vTable") Populate = ds.Tables("vTable").DefaultView

End Function

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Mtodo RunSql.

Function RunSql(vsql as string) as StringDim Message As String = ""

Dim errString As String = ""

try

Dim myConnection As SqlConnectionmyConnection = New SqlConnection(ConnStr)

Dim mycommand As New SqlCommand(vsql,myConnection)

myconnection.Open()myCommand.ExecuteNonQuery()

myconnection.Close()

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Catch ex As SqlException

Dim errItem As SqlError

For Each errItem In ex.Errors

errString += ex.Message + " "

Next

Message = "SQL Error.Details follow:

" & errStringCatch myException as Exception

message = "Exception: " + myException.ToString()

End try

RunSql = message

End FunctionEnd Class

End Namespace

Mtodo RunSql

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Imports

Imports BC_Bhasin_Capitulo_08.SQLNameSpace

Partial Class TestVbClass

Inherits System.Web.UI.Page

Dim Comp As SQLClass

Dim ConnStr As String

Dim SQL As String

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Load

Sub Page_Load(ByVal Source As Object, ByVal E

As EventArgs)

Comp = New SQLClass()

Comp.ConnStr= "Data Source=(local);InitialCatalog=ASPNET;Integrated Security=True;"

If Not (IsPostBack) Then

ReBind()End If

End Sub

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Insert

Sub Insert_click(ByVal Sender As Object, ByVal E

As EventArgs)

SQL = "Insert into

Masters(code_display,code_category,type)"SQL = SQL + "Values ('test',701,'E')"

Comp.RunSql(SQL)

ReBind()Message.Text = "Inserted test record... "

End Sub

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Delete

Sub Delete_click(ByVal Sender As Object, ByVal E

As EventArgs)

SQL = delete from masters where

code_display = test Comp.RunSql(SQL)

ReBind()

Message.Text = Deleted all test records...End Sub

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Update

Sub Update_Click(ByVal Sender As Object, ByVal

E As EventArgs)

SQL = "UPDATE Masters Set Opening = 90

WHERE code_display = 'test'"

Comp.RunSQL(SQL)

ReBind()

Message.Text = "Updated all test records:Set closing balance = 90...! "

End Sub

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rebind

Sub ReBind()

Comp.SQL = "select * from Masters"

DataGrid1.DataSource =Comp.populate()

DataGrid1.DataBind()

End Sub