VB.NET Sql Command Delete Statement Source Code Example


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VB.NET Sql Command Delete Statement Source Code

Purpose: – Illustrates using and checking the result.
Prerequistes:

  1. Install Visual Basic (Express or Standard Edition)
  2. Install SQL Server Express
  3. Download Northwind Database
  4. Attach Northwind Database to Databases in Sql Express

Notes:

  • Console Application is used to simplify things, but Windows Forms or Web Forms could also be used
  • You can build a library of syntax examples by using same project over and over and just commenting out what you do not want to execute in Module1.vb

Instructions:

  1. Use VB 2008 (Express or Standard) Edition
  2. Create new project; select Console Application; name of Project could be VBNET_Syntax.
  3. Right-click project name in solution explorer; add new folder; name of folder could be DatabaseADONET
  4. Right-click folder; add class; class name could be clsSqlCommandDelete.vb
  5. Copy code into clsSqlCommandDelete.vb
  6. Copy code into Module1.vb
  7. Click green arrow to start with debugging

Step 1: Use View Plain to Cut-n-paste code into clsSqlCommandDelete.vb

 Visual Basic |  copy code |? 
 
Imports System
Imports System.Data
Imports System.Data.SqlClient
 
Public Class clsSqlCommandDelete
    Sub Main()
        Dim thisConnection As New SqlConnection("server=(local)\SQLEXPRESS;" & _
            "integrated security=sspi;database=Northwind")
        'First insert some records
        'Create Command object
        Dim nonqueryCommand As SqlCommand = thisConnection.CreateCommand()
 
        Try
            ' Open Connection
            thisConnection.Open()
            Console.WriteLine("Connection Opened")
 
            ' Create INSERT statement with named parameters
            nonqueryCommand.CommandText = _
               "INSERT  INTO Employees (FirstName, LastName) VALUES (@FirstName, @LastName)"
 
            ' Add Parameters to Command Parameters collection
            nonqueryCommand.Parameters.Add("@FirstName", SqlDbType.VarChar, 10)
            nonqueryCommand.Parameters.Add("@LastName", SqlDbType.VarChar, 20)
 
            ' Prepare command for repeated execution
            nonqueryCommand.Prepare()
 
            ' Data to be inserted
            Dim names() As String = {"Wade", "David", "Charlie"}
            For i As Integer = 0 To 2
                nonqueryCommand.Parameters("@FirstName").Value = names(i)
                nonqueryCommand.Parameters("@LastName").Value = names(i)
 
                Console.WriteLine("Executing {0}", _
                   nonqueryCommand.CommandText)
                Console.WriteLine("Number of rows affected : {0}", _
                   nonqueryCommand.ExecuteNonQuery())
            Next i
        Catch ex As SqlException
            ' Display error
            Console.WriteLine("Error: " & ex.ToString())
        Finally
            ' Close Connection
            thisConnection.Close()
            Console.WriteLine("Connection Closed")
 
        End Try
 
 
 
        Try
            ' Open Connection
            thisConnection.Open()
            Console.WriteLine("Connection Opened")
 
 
 
            'Create Command objects
            Dim scalarCommand As New SqlCommand("SELECT COUNT(*) FROM Employees", thisConnection)
 
            ' Execute Scalar Query
            Console.WriteLine("Before Delete, Number of Employees = {0}", _
               scalarCommand.ExecuteScalar())
 
 
            ' Set up and execute DELETE Command
            nonqueryCommand.CommandText = _
               "DELETE FROM Employees WHERE " & _
               "Firstname='Wade' AND Lastname='Wade' or " & _
               "Firstname='Charlie' AND Lastname='Charlie' or " & _
               "Firstname='David' AND Lastname='David' "
            Console.WriteLine("Executing {0}", nonqueryCommand.CommandText)
            Console.WriteLine("Number of rows affected : {0}", _
               nonqueryCommand.ExecuteNonQuery())
 
            ' Execute Scalar Query
            Console.WriteLine("After Delete, Number of Employee = {0}", _
               scalarCommand.ExecuteScalar())
 
        Catch ex As SqlException
            ' Display error
            Console.WriteLine("Error: " & ex.ToString())
        Finally
            ' Close Connection
            thisConnection.Close()
            Console.WriteLine("Connection Closed")
 
        End Try
        Console.ReadLine()
    End Sub
End Class
 

Step 2: Use View Plain to Cut-n-paste code into Module1.vb
 Visual Basic |  copy code |? 
Module Module1
 
    Sub Main()
        '***** DataBaseADONET *************
 
        'Dim mySQLConnectionConnectionString As New clsSQLConnectionConnectionString
        'mySQLConnectionConnectionString.Main()
 
        'Dim mySQLInsert As New clsSQLInsert
        'mySQLInsert.Main()
 
        'Dim mySQLParameters As New clsSQLParameters
        'mySQLParameters.Main()
 
        'Dim mySQLCallStoredProcedure As New clsSQLCallStoredProcedure
        'mySQLCallStoredProcedure.Main()
 
        'Dim mySQLSelect As New clsSQLSelect
        'mySQLSelect.Main()
 
        Dim mySqlCommandDelete As New clsSqlCommandDelete
        mySqlCommandDelete.Main()
 
 
 
    End Sub
 
End Module
 
 

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