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# Chapter 5. Alter data of a column

We alter now the data of the column. Just give the new value as a parameter to the method hk_column::set_asstring().

Example 5-1. Alter 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    mycolumn->set_asstring("my new data");
      23    mydatasource->store_changed_data();
      24    delete mydrivermanager;
      25 }

The method mydatasource->store_changed_data(); will store the changes. The data will also be stored when you move the rowselector to another row (hk_datasource::goto_row()) or when you disable the datasource (hk_datasource::disable()).

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