In this web project, the query builder was designed as a
user control that can be called from several parent pages such as Search
Person, Search Platform, and Search ID. The figure below shows the design form
of query builder and data grid. The query builder consists of four key elements:
T-SQL operator (e.g., AND), query attribute which is dynamically read from
tables (e.g., Last Name), query operator (e.g., Begins With), and the HTML control
which are based on the attribute data types (e.g., text boxes, list boxes or
calendar controls).
Web Form with AJAX
With the implementation of AJAX, only changes are updated on
the web form. Other sections remain unchanged. This avoids unnecessary full
page reloading.
Event Code
Users can easily compose the query context such as adding
queries to filter list, deleting query item, or navigating the filter through
the list. Update panel makes sure only the list box is posted back. See the C#
code snippets:
Listing 1 - Add List Item
protected void btnAddFilter_OnClick(object sender, EventArgs e)
{
string filterText = "", filterValue = "", filterTextValue = "";
if (lstCriteria.Items.Count > 0)
{
filterText = ddlANDOR.SelectedItem.Text + " ";
filterValue = ddlANDOR.SelectedItem.Text + ";";
filterTextValue = ddlANDOR.SelectedItem.Text + ";";
}
filterText += ddlCols.SelectedItem.Text + " ";
filterTextValue += ddlCols.SelectedItem.Text + ";";
filterValue += ddlCols.SelectedValue + ";";
filterText += ddlOperator.SelectedValue + " ";
filterValue += ddlOperator.SelectedValue + ";";
filterTextValue += ddlOperator.SelectedValue + ";";
filterText += txtCriteria.Text.Trim();
filterTextValue += txtCriteria.Text.Trim();
filterValue += txtCriteria.Text.Trim();
lstCriteria.Items.Add(new ListItem(filterText, filterTextValue +
"|" + filterValue));
upCriteria.Update();
}Listing 2 - Delete List Item
protected void btnRemove_OnClick(object sender, EventArgs e)
{
if ((lstCriteria.SelectedIndex == 0) && (lstCriteria.Items.Count > 1))
{
ListItem item = lstCriteria.Items[1];
int idx = item.Text.IndexOf(' ');
string strAndOr = item.Text.Substring(0, idx);
string[] itemValues = item.Value.Split("|".ToCharArray());
string filterTextValue = itemValues[0].Substring(idx + 1,
itemValues[0].Length - idx - 1);
string filterValue = itemValues[1].Substring(idx + 1,
itemValues[1].Length - idx - 1);
item.Text = item.Text.Substring(idx + 1, item.Text.Length - idx - 1);
item.Value = filterTextValue + "|" + filterValue;
}
lstCriteria.Items.RemoveAt(lstCriteria.SelectedIndex);
}Listing 3 - Move Up List Item
protected void btnUp_OnClick(object sender, EventArgs e)
{
if (lstCriteria.SelectedIndex == 1)
{
ListItem item = lstCriteria.SelectedItem;
ItemMove(item);
}
if (lstCriteria.SelectedIndex > 0)
{
int idxSelected = lstCriteria.SelectedIndex;
int idxOther = idxSelected - 1;
lstCriteria.Items.Insert(idxSelected + 1,
lstCriteria.Items[idxOther]);
lstCriteria.Items.RemoveAt(idxOther);
}
}Listing 4 - Move Down List Item
protected void btnDown_OnClick(object sender, EventArgs e)
{
if ((lstCriteria.SelectedIndex == 0) && (lstCriteria.Items.Count > 1))
{
ListItem item = lstCriteria.Items[1];
ItemMove(item);
}
if (lstCriteria.SelectedIndex < lstCriteria.Items.Count - 1)
{
int idxSelected = lstCriteria.SelectedIndex;
int idxOther = idxSelected + 1;
lstCriteria.Items.Insert(idxSelected, lstCriteria.Items[idxOther]);
lstCriteria.Items.RemoveAt(idxOther + 1);
}
} 
