c# - Three tiers select date from two tables -

i have tried googling lot of things, couldn't find answer - hoping me out!

what i'm trying do: on winform application need select computername through combobox, upon selection, listbox populated data computer (softwarename, version , stuff)

the combobox working id, not other fields.

my listview, using database call, listed bellow:

clsoftwareperpc sf = new clsoftwareperpc(); datatable dt = sf.selectsoftware(zoekid);    // voor iedere rij een nieuw nummer geven (r) (int r = 0; r < dt.rows.count; r++) {     lvi = new listviewitem();     // cdnummer als titel     //lvi.text = (string)(dt.rows[r]["idcomputer"]);     lvi.text = ((string)(dt.rows[r]["idinstallatie"]).tostring());     // titels toevoegen in deze kolom     lvi.subitems.add((string)(dt.rows[r]["softwarenaam"]));     lvi.subitems.add((string)(dt.rows[r]["ontwikkelaar"]));     lvi.subitems.add((string)(dt.rows[r]["omschrijving"]));     lvi.subitems.add((string)(dt.rows[r]["versie"]));     lvi.subitems.add(((string)(dt.rows[r]["updatedatum"]).tostring()));     lvi.tag = (((string)(dt.rows[r]["idinstallatie"]).tostring()));     // alle opgevraagde velden weergeven     lv.items.add(lvi); } // wanneer er records zijn if (dt.rows.count > 0) {     // eerste rij selecteren     lv.items[0].selected = true;     lv.select(); } 

my database call (working , tested) / clsoftwareperpc:

public datatable selectsoftware(string zoekid) {     // selecteren van alle inhoud van tabel computers en orderen op merk naam     // string sql = "select * softwareopcomputer order idcomputer model = '" + zoekid + "'";     string sql = "select * software, softwareopcomputer software.idsoftware = softwareopcomputer.idsoftware , softwareopcomputer.idcomputer =  '" + zoekid + "'";     // uitoveren van query     return cldatabase.executeselect(sql); } 

* select now: select * [table names] i've tried use full location one: software.version, didn't work either. zoekid value combobox selected computer.

the database: databse looks this: pbs.twimg.com/media/bjw-wd9cmaaczio.jpg:large need fields like: softwareopcomputer.versie, softwareopcomputer.updatedatum, software.softwarenaam, software.ontwikkelaar.

when use method , use 1 table (the other pages of application) works, when use screen , need 2 tables doesn't work.

i try use join instead.

 string sql = "select c.versie, c.updatedatum, s.softwarenaam, s.ontwikkelaarfrom " +               "from software s inner join softwareopcomputer c " +                "on s.idsoftware = c.idsoftware " +                "where c.idcomputer =  '" + zoekid + "'"; 

this produce join between software , sotwareopcomputer. returns rows software , softwareopcomputer tables have matched id excluding rows don't have matching id , condition limits output.

unfortunately, use method cldatabase.executeselect doesn't seem allow pass parameter avoid string concatenation. suggest search parametrized query , sql injection realize how code weak

here documentation on join

another aspect wish improve loop add rows listview

foreach (datarow row in dt.rows) {     lvi = new listviewitem();     lvi.text = row.field<string>("idinstallatie"));     lvi.subitems.add(row.field<string>("softwarenaam"));     .... etc ...  }