How to create an array of templated class objects?

Field<T1> and Field<T2> are two completely different types. To treat them in a vector you need to generialize then somewhere. You may write AbstractField and

struct AbstractField{  virtual ~AbstractField() = 0;};template<class T,int fieldTypeId>class Field: public AbstractField{  private:    T field;  public:    const static int field_type;  public:    virtual ~Field(){}};class Database_Record{  std::vector<AbstractField*> record;   public:    ~Database_Record(){      //delete all AbstractFields in vector    }};

and then keep a vector of AbstractField. also use vector instead of []. Use AbstractField* instead of AbstractField and write at least one pure virtual in AbstractField.

you may make the destructor of AbstractField pure virtual. and don't forget to delete all AbstractFields. in ~Database_Record()

You are going the wrong way.

Templates are used to create distinct types: std::vector<int> and std::vector<float> are distinct in much the same way (and as much) as int and float are.

Your syntax is also wrong; to create a dynamic array you'd put the following member in your Database_Record:

 std::vector<Field> record; // if this was possible; however, it's not

To put several objects of distinct type into a single array, they ought to have a common base class.

In order to create an array of different types you need a base class for the objects and the array will be an array of pointers to that base class. So, for example,

class Field{public:    virtual ~Field() {}    virtual std::string toString() const = 0;    // and possibly other interface functions...};template <class T> FieldImpl : public Field{public:    virtual std::string toString() const    {        std::stringstream ss;        ss << val;        return ss.str();    }    // implementation of possibly other interface functions        private:    T val;}

will be the types you need. The array will then be something like

std::vector<std::unique_ptr<Field>> my_array;

You can then do stuff with your array using the interface functions, e. g.

my_array[i]->toString();