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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<HTML
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>Show data of a column</TITLE
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>Chapter 4. Show data of a column</H1
><P
>&#13;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-&#62;asstring().
 The hk_datasource::column_by_name method allows you to select a
column by it's name.</P
><P
>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:
<UL
><LI
STYLE="list-style-type: disc"
><P
>bool  goto_row (unsigned long r)</P
></LI
><LI
STYLE="list-style-type: disc"
><P
>bool  goto_first (void)</P
></LI
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>bool  goto_last (void)</P
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>bool  goto_next (void)</P
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>Example 4-1. Show data of a column</B
></P
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><PRE
CLASS="PROGRAMLISTING"
>   1&nbsp;#include &#60;hk_classes.h&#62;
   2&nbsp;#include &#60;iostream&#62;
   3&nbsp;int main()
   4&nbsp;{
   5&nbsp;   hk_drivermanager* mydrivermanager = new hk_drivermanager();
   6&nbsp;   if (mydrivermanager==NULL) {cout &#60;&#60;"error creating mydrivermanager"&#60;&#60;endl;exit(1);}
   7&nbsp;   hk_connection* myconnection = mydrivermanager-&#62;new_connection("mysql");
   8&nbsp;   if (myconnection==NULL) {cout &#60;&#60;"error creating myconnection"&#60;&#60;endl;exit(1);}
   9&nbsp;   myconnection-&#62;set_host("localhost");
  10&nbsp;   myconnection-&#62;set_user("root");
  11&nbsp;   myconnection-&#62;set_password("mypasswd");
  12&nbsp;   myconnection-&#62;connect();
  13&nbsp;
  14&nbsp;   hk_database* mydatabase=myconnection-&#62;new_database("exampledb");
  15&nbsp;   if (mydatabase==NULL) {cout &#60;&#60;"error creating mydatabase"&#60;&#60;endl;exit(1);}
  16&nbsp;   hk_datasource* mydatasource= mydatabase-&#62;new_table("authors");
  17&nbsp;   if (mydatasource==NULL) {cout &#60;&#60;"error creating mydatasource"&#60;&#60;endl;exit(1);}
  18&nbsp;   mydatasource-&#62;enable();
  19&nbsp;
  20&nbsp;   <FONT
COLOR="RED"
>hk_column* mycolumn = mydatasource-&#62;column_by_name("name");</FONT
>
  21&nbsp;   <FONT
COLOR="RED"
>if (mycolumn==NULL) {cout &#60;&#60;"error getting column"&#60;&#60;endl;exit(1);}</FONT
>
  22&nbsp;   <FONT
COLOR="RED"
>cout &#60;&#60;"Value of the first row: "&#60;&#60;mycolumn-&#62;asstring()&#60;&#60;endl;</FONT
>
  23&nbsp;   <FONT
COLOR="RED"
>mydatasource-&#62;goto_next();</FONT
>
  24&nbsp;   <FONT
COLOR="RED"
>cout &#60;&#60;"Value of the second row: "&#60;&#60;mycolumn-&#62;asstring()&#60;&#60;endl;</FONT
>
  25&nbsp;
  26&nbsp;   delete mydrivermanager;
  27&nbsp;}</PRE
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