Use Variable in query

David Carter

I have an OleDbAdapter attached to a datagridview.
I wish to take the value in a textbox to use in a query to fill the datagridview.
Eg. The following works: David Carter in this instance is typed into the Query as a constant.
OleDbDataAdapter1.SelectCommand.CommandText = "Select * From InfringementRecords Where([INFStudent] = 'David Carter')"
But I don't want David Carter to be fixed in the query, I want to use a variable as entered into a textbox
Dim SelectName as string
SelectName = Textbox1.text
OleDbDataAdapter1.SelectCommand.CommandText = "Select * From InfringementRecords Where([INFStudent] = " & SelectName & ")"
That gives me an error:
Syntax error (missing operator) in query expression '([INFStudent] = David Carter)'.
Does anyone know how to use a variable in a query?
Visual Studio 2008.
Regards,
David

4 Replies

Know the answer? Post it — somebody with the same question will find it here.

Satyapriya Nayak16y ago
Accepted answer
Hi David,

Here is the vb code below:-

Imports System.Data
Imports System.Data.OleDb
Public Class Form1
    Dim ConnectionString As String = System.Configuration.ConfigurationSettings.AppSettings("dsn")
    Dim con As OleDbConnection
    Dim com As OleDbCommand
    Dim oledbda As OleDbDataAdapter
    Dim ds As DataSet
    Dim str As String
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        bind()
    End Sub
    Sub bind()
        con = New OleDbConnection(ConnectionString)
        con.Open()
        Str = "select * from employee"
        com = New OleDbCommand(Str, con)
        oledbda = New OleDbDataAdapter(com)
        ds = New DataSet()
        oledbda.Fill(ds, "employee")
        DataGridView1.DataSource = ds
        DataGridView1.DataMember = "employee"
        con.Close()
    End Sub

    Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
        con = New OleDbConnection(ConnectionString)
        con.Open()
        str = "select * from employee where empname like '" & TextBox1.Text & "%'"
        com = New OleDbCommand(Str, con)
        oledbda = New OleDbDataAdapter(com)
        ds = New DataSet()
        oledbda.Fill(ds, "employee")
        DataGridView1.DataSource = ds
        DataGridView1.DataMember = "employee"
        con.Close()
    End Sub
End Class

Thanks

If it helps you plz mark it as Accepted answer
David Carter16y ago
Thank you very much.
The line I needed was:
OleDbDataAdapter1.SelectCommand.CommandText = "Select * From InfringementRecords Where([INFStudent] = '" & SelectName & "')"
I was missing the ' after the = sign and before the )"
The % seemed to be incorrect.
Regards,
David
David Carter16y ago
Thanks for your efforts.
I'm using VB.
Regards,
David
Satyapriya Nayak16y ago
Hi David,
This is a simple application i did it of your requirement.Run the attachments.
Code:-
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.OleDb;
namespace Display_data_in_datagridview_with_textbox
{
    public partial class Form1 : Form
    {
        string ConnectionString = System.Configuration.ConfigurationSettings.AppSettings["dsn"];
        OleDbCommand com;
        OleDbDataAdapter oledbda;
        DataSet ds;
        string str;
        public Form1()
        {
            InitializeComponent();
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            bindgrid();
        }
        void bindgrid()
        {
            OleDbConnection con = new OleDbConnection(ConnectionString);
            con.Open();
            str = "select * from employee";
            com = new OleDbCommand(str, con);
            oledbda = new OleDbDataAdapter(com);
            ds = new DataSet();
            oledbda.Fill(ds, "employee");
            dataGridView1.DataSource = ds;
            dataGridView1.DataMember = "employee";
            con.Close();
        }
        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            OleDbConnection con = new OleDbConnection(ConnectionString);
            con.Open();
            str = "select * from employee where empname like '" + textBox1.Text + "%'";
            com = new OleDbCommand(str, con);
            oledbda = new OleDbDataAdapter(com);
            ds = new DataSet();
            oledbda.Fill(ds, "employee");
            dataGridView1.DataSource = ds;
            dataGridView1.DataMember = "employee";
            con.Close();
        }
    }
}

Thanks

If it helps you plz mark it as Accepted answer