Imports System.Data.OleDb
'For sqlserver
'Imports System.Data.SqlClient
'CrystalDecisions.CrystalReports.Engine is a dll which is used for the creation of reports.
Imports CrystalDecisions.CrystalReports.Engine
Public Class Reportcode
    Dim con As OleDbConnection
    'dim con As SqlConnection (For sqlconnection)
    'DataTable is used for the storage of data which we get from the database
    Dim dt As DataTable
    'Dataadapter is used to fill the data from the database into datatable
    Dim da As OleDbDataAdapter
    'Reportdocument is bind with the reportviewer to show the report.
    Dim obj As New ReportDocument
    'StringBuilder is class used to build multiple strings and create the sentence.
    Dim str As New System.Text.StringBuilder
    Private Sub Reportcode_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        str.Append("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=")
        'AppDomain.CurrentDomain.BaseDirectory will give you path of debug folder in your current solution
        Str.Append(AppDomain.CurrentDomain.BaseDirectory)
        str.Append("test.mdb")
        Str.Append(";Persist Security Info=False")
        con = New OleDbConnection
        'ConnectionString is property used for the connecting with the database.
        con.ConnectionString = str.ToString
        'For sqlconnection
        'con.ConnectionString = "workstation id=HOME;packet size=4096;integrated security=SSPI;initial catalog=IMS" & _
        '                  ";persist security info=False"
        'Distinct keywords gives you data which is not duplicated in table.
        da = New OleDbDataAdapter("select distinct(deptno) from emp", con)
        dt = New DataTable
        da.Fill(dt)
        'To bind datatable with combobox
        cmbdept.DataSource = dt
        'DisplayMember is used to show the data of particular column
        cmbdept.DisplayMember = "Deptno"
        da = Nothing
        dt = Nothing
    End Sub
    Private Sub cmdreport_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdreport.Click
        Dim cmd As New OleDbCommand
        Dim str1 As String
        Dim str2 As String
        dt = New DataTable
        cmd.Connection = con
        cmd.CommandType = CommandType.Text
        cmd.CommandText = "Select * from emp where deptno=" & Val(cmbdept.Text)
        da = New OleDbDataAdapter(cmd)
        da.Fill(dt)
        Dim str As String
        str = AppDomain.CurrentDomain.BaseDirectory
        str1 = str.Remove(str.IndexOf("bin"), 10)
        str2 = str1 & "RptCode.rpt"
        'MsgBox(str2)
        'Str1 contains the path of report.
        obj.Load(str1 & "RptCode.rpt")
        'Binding the table with the reportdocument object
        obj.Database.Tables(0).SetDataSource(dt)
        'Binding the document with the reportviewer control
        CrystalReportViewer1.ReportSource() = obj
    End Sub
End Class

<img src="c:\report.jpg">