ASP.NET - ConstraintException was unhandled by user code

Been dabbling with a bit of ASP.NET. I current have the following error:

Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints

It breaks on the following line:

开发者_如何学C DataTable propertyTable = pta.searchByType(sType);

Code:

String sType = Request.QueryString["type"];
DataSetTableAdapters.propertiesTableAdapter pta = new DataSetTableAdapters.propertiesTableAdapter();
DataTable propertyTable = pta.searchByType(sType);
if (propertyTable.Rows.Count > 0)
{
    lblStatus.Text = "Your Results";
    gvProperty.DataSource = propertyTable;
    gvProperty.DataBind();
}

The query that pta.searchByType(sType); is calling is:

SELECT     property_id, name, description, price, image, town
FROM         properties
WHERE     (date_approved IS NOT NULL) AND (property_type = @property_type)

The primary key for the properties table is property_id, the table has one FK that links to a users table but that's it.

Any help pointing me in the right direction is great. If you need any more details just drop them in the comments below.

Thanks :)

Are you selecting ALL the columns?

See: http://forums.asp.net/t/1400495.aspx/1

You can always cheat and set enable constraints to false on the table adapter, too.