select table_name
from information_schema.referential_constraints
where referenced_table_name = 'parent table here';
Я бы использовал WebClient.UploadValues
:
using (WebClient client = new WebClient())
{
NameValueCollection fields = new NameValueCollection();
fields.Add("query", query);
byte[] respBytes = client.UploadValues(url, fields);
string resp = client.Encoding.GetString(respBytes);
}