Сделать поиск по выбранному полю в таблице

dataGridViewSectionData.DataSource = context.Database.SqlQuery<String>("Select * From SectionDataUmcView Where [" + comboBoxSearch.Text + "] = '" + comboBoxSearchItem.Text + "'").ToList();

BindingSource bs = new BindingSource();//поле класса-формы
Form_Load
{
using(SqlConnection conn ...)
{
    SqlDataAdapter ada = new SqlDataAdapter("Select * From SectionDataUmcView", conn);
    DataTable dt = new DataTable();
    ada.Fill(dt);
    bs.DataSource = dt;
    dataGridViewSectionData.DataSource = bs;
}
}
comboBoxSearch_SelectedIndexChanged
{
     bs.Filter = comboBoxSearch.Text + "=" + textBoxSearchItem.text;
}
 
textBoxSearchItem_TextChanged
{
   bs.Filter = comboBoxSearch.Text + "=" + textBoxSearchItem.text;
}

dataGridViewSectionData.DataSource = context.SectionDataUmcViews.SqlQuery("Select * From SectionDataUmcView Where [" + comboBoxSearch.Text + "] = " + comboBoxSearchItem.Text + "").ToList();

using (var context = new UMCEntities())
            {
                dataGridViewSectionData.DataSource = context.SectionDataUmcViews.SqlQuery("Select * From SectionDataUmcView Where [" + comboBoxSearch.Text + "] = '" + comboBoxSearchItem.Text + "'").ToList();
            }