How do I implement a select count (*) in DBTools.h++?

As a database programmer, you may want to get a count of the total number of rows
in a table or the number of rows that meet certain criteria.

With rowCount() method available in the RWDBResult class you can only get the rows inserted or updated or deleted
but not the rows selected.  

Here is a code snippet demonstrating how to implement a row count using the DBTools.h++ selector object.

      RWDBTable table = db.table(tableX);
      RWDBSelector select = db.selector();
      select << rwdbCount(table[anycolumn]);

The above statements will produce a SQL statement like:

     SELECT COUNT(table.anycolumn)

You can also use this form:

     select << rwdbCount();
     select.from(table);

OR

     select.from(tableX);

and the SQL statement produced will look like this:

     SELECT COUNT(*) FROM tableX t0

You can also add a where clause with any criteria desired by using the where() method on the selector.

Now you have to use RWDBReader to read the number of rows selected.

RWDBReader rdr = select.reader(conn);
int numberOfRows;
while(rdr())
{
  rdr >> numberOfRows;
  cout << numberOfRows << endl;
}