Following section demonstrates using Count extension, to get count of row(s).

		// Table Aliases
        var t0 = new Orders().AsQueryable();

		// Query
        var query = Odb.SQL.Select(x => x.From(t0));

		// Read
        var result = cn.{{hl}}Count(query){{/hl}};

SELECT COUNT(1) FROM [Orders] AS t0 dRfL97

Limitations of Count extension.

All selection fields are ignored and only value of the COUNT() is returned.
All rows are counted regardless the field values.
Order clause is ingored, because it is not necessary.

To counting the field values by excluding NULL values, you have to use COUNT with a column.

		// Table Aliases
        var t0 = new Orders().AsQueryable();

        using(var exc = cn.Executer()) {

            var query = Odb.SQL.Select(x => x.From(t0).Fields( {{hl}}x[t0.OrderID].COUNT(){{/hl}} ));

            var result = (int?)(cn.Sql(query).Read().FirstOrDefault()?[0]) ?? 0;

        }

SELECT COUNT(t0.OrderID) FROM [Orders] AS t0 dRfL97