public void CountAll()
{
var result = SelectAggregate("COUNT", SqlExpression.Constant("*"));
Assert.IsNotNull(result);
Assert.IsFalse(result.IsNull);
Assert.IsInstanceOf<NumericType>(result.Type);
Assert.IsInstanceOf<SqlNumber>(result.Value);
var value = (SqlNumber)result.Value;
Assert.AreEqual(new SqlNumber(15), value);
}