The hk_classes programmer's tutorial
Prev |  | Next

# Chapter 4. Show data of a column

Now we try to show data of a specific column. For this we get a hk_column object. hk_column represents a specific column of a datasource. To display the data of the actual row use the command mycolumn->asstring(). The hk_datasource::column_by_name method allows you to select a column by it's name.

When you enable a datasource the row selector is in row 0 (the first row). To move the row selector use one of the hk_datasource methods:

- bool goto_row (unsigned long r)

- bool goto_first (void)

- bool goto_last (void)

- bool goto_next (void)

- bool goto_previous (void)

Example 4-1. Show data of a column

       1 #include <hk_classes.h>
       2 #include <iostream>
       3 int main()
       4 {
       5    hk_drivermanager* mydrivermanager = new hk_drivermanager();
       6    if (mydrivermanager==NULL) {cout <<"error creating mydrivermanager"<<endl;exit(1);}
       7    hk_connection* myconnection = mydrivermanager->new_connection("mysql");
       8    if (myconnection==NULL) {cout <<"error creating myconnection"<<endl;exit(1);}
       9    myconnection->set_host("localhost");
      10    myconnection->set_user("root");
      11    myconnection->set_password("mypasswd");
      12    myconnection->connect();
      13
      14    hk_database* mydatabase=myconnection->new_database("exampledb");
      15    if (mydatabase==NULL) {cout <<"error creating mydatabase"<<endl;exit(1);}
      16    hk_datasource* mydatasource= mydatabase->new_table("authors");
      17    if (mydatasource==NULL) {cout <<"error creating mydatasource"<<endl;exit(1);}
      18    mydatasource->enable();
      19
      20    hk_column* mycolumn = mydatasource->column_by_name("name");
      21    if (mycolumn==NULL) {cout <<"error getting column"<<endl;exit(1);}
      22    cout <<"Value of the first row: "<<mycolumn->asstring()<<endl;
      23    mydatasource->goto_next();
      24    cout <<"Value of the second row: "<<mycolumn->asstring()<<endl;
      25
      26    delete mydrivermanager;
      27 }

Prev | Home | Next
Preselect the driver and user information |  | Alter data of a column