MySQL++

MySQL version: mysql-5.7.23-win32
OS: Windows 10 1809
Visual Studio: vs2015 update 3

    I built mysql++-3.2.4 in its vc2005 project and got the x86 lib. I did some modification in the resetdb.cpp and ran the resetdb project, then I found a problem.

```
                // Now create empty images table, for testing BLOB and auto-
		// increment column features.
		cout << "Creating empty images table..." << endl;
		query.reset();		// forget template query info
		query << 
				"CREATE TABLE images (" <<
				"  id INT UNSIGNED AUTO_INCREMENT, " <<
				"  data BLOB, " <<
				"  PRIMARY KEY (id)" <<
				")";
		query.execute();
        query.execute( "insert into images (data) values (\"def\")");

        query << "insert into %1:tab (%2:field) values (%0q:val1)";
        //query << "insert into %0:table values (\"def\")";
        query.parse();
        query.template_defaults["tab"] = "images";
        query.template_defaults["field"] = "data";
        query.template_defaults["val1"] = "abc";
        //query.template_defaults["field"] = "data";
        cout << query.str() << endl;
        query.execute("abc", "images");
        query.execute("images");
        query.reset();
```

    A BadQuery was caught when executing `query.execute("images");`. I debuged and waited in mysql_real_query(...), then I found that the `qstr` is "images".

    I think it's something wrong when there're more than one placeholder but pass only one parameter into execute(...).

    If it's not a bug, please give me some advice on how to do in this situation.