SELECT Query WHERE multiple values from checkboxlist are used - sql

Question

I was wondering if it was possible to filter down data from a table using multiple values from a checkboxlist? (or any other way) I have a checkboxlist and a gridview and when you check on of the boxes it does show the right data in the gridview but the problem arises when I try to check multiple values. It seems to search for the first checked value and then ignores the rest. You'd think it'd be simple! Perhaps it is. Here is my attempt below.
CODE BEHIND
Imports System.Data
Imports System.Data.SqlClient
Partial Class Default2
Inherits System.Web.UI.Page
Dim strSQL As New System.Text.StringBuilder
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Page.IsPostBack Then
Dim i As Integer, c As Integer = 0
Dim strParams As String = ""
For i = 0 To Me.CheckBoxList1.Items.Count - 1
If CheckBoxList1.Items(i).Selected Then
c += 1
If c = 1 Then
strParams = "(Keyword.Keyword = '" & CheckBoxList1.Items(i).Text & "')"
Else
strParams &= " AND (Keyword.Keyword = '" & CheckBoxList1.Items(i).Text & "')"
End If
End If
Next
strSQL.Append("SELECT Project.*")
strSQL.Append(" FROM Keyword INNER JOIN Project ON Keyword.ProjID = Project.ProjID")
strSQL.Append(" WHERE" & strParams)
FillGridView()
End If
End Sub
Private Sub FillGridView()
Dim strMyConn As String = "Data Source=(LocalDB)\v11.0;AttachDbFilename=|DataDirectory|\FYPMS_DB.mdf;Integrated Security=True"
Using MyConn As New SqlClient.SqlConnection(strMyConn)
MyConn.Open()
Dim cmd As New SqlClient.SqlCommand(strSQL.ToString, MyConn)
cmd.Connection = MyConn
cmd.CommandType = CommandType.Text
Try
Using dr As SqlClient.SqlDataReader = cmd.ExecuteReader
Dim dt As New DataTable
dt.Load(dr)
Me.GridView1.DataSource = dt
Me.GridView1.DataBind()
End Using
If Me.GridView1.Visible = False Then Me.GridView1.Visible = True
Catch ex As Exception
Me.GridView1.Visible = False
End Try
End Using
End Sub
Protected Sub CheckBoxList1_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs)
Dim i As Integer, c As Integer = 0
Dim strParams As String = ""
For i = 0 To Me.CheckBoxList1.Items.Count - 1
If CheckBoxList1.Items(i).Selected Then
c += 1
If c = 1 Then
strParams = "(Keyword.Keyword = '" & CheckBoxList1.Items(i).Text & "')"
Else
strParams &= " AND (Keyword.Keyword = '" & CheckBoxList1.Items(i).Text & "')"
End If
End If
Next
If c <> 0 Then
strSQL.Append("SELECT Project.*")
strSQL.Append(" FROM Keyword INNER JOIN Project ON Keyword.ProjID = Project.ProjID")
strSQL.Append(" WHERE" & strParams)
End If
End Sub
End Class

Answer 1

Refactor this section to create a WHERE IN statement so it checks to see if the value is found among any item checked
Before
Dim strParams As String = ""
For i = 0 To Me.CheckBoxList1.Items.Count - 1
If CheckBoxList1.Items(i).Selected Then
c += 1
If c = 1 Then
strParams = "(Keyword.Keyword = '" & CheckBoxList1.Items(i).Text & "')"
Else
strParams &= " AND (Keyword.Keyword = '" & CheckBoxList1.Items(i).Text & "')"
End If
End If
Next
After
Dim params As StringBuilder = New StringBuilder()
For i = 0 To Me.CheckBoxList1.Items.Count - 1
If CheckBoxList1.Items(i).Selected Then
params.Append("'")
params.Append(CheckBoxList1.Items(i).Text)
If i < Me.CheckBoxList1.Items.Count Then
params.Append("',") // don't append a comma if it's the last item
End If
End If
Next
strSQL.Append("SELECT Project.* FROM Keyword INNER JOIN Project ON Keyword.ProjID = Project.ProjID WHERE Keyword.Keyword in (")
strSQL.Append(params.ToString()) // append comma delimited values that make up where in statement
strSQL.Append("')") // close where in statement
FillGridView()