c# - dropdownlist Select from SQL database -

i'm trying project car maintenance, , have small problem. project like:

4 kind of maintenance plans different cars.

 cara ( mirrora, etc etc )  carb ( mirrorb, etc etc )  carc ( mirrorc, etc etc )  card ( mirrord, etc etc ) 

what i'm trying when chose car (from dropdownlist), program selects right maintenance plan car!

sqlcommand cmd = new sqlcommand("select id, description accauto_maps", con); con.open(); dropdownlist1.datasource = cmd.executereader(); dropdownlist1.datatextfield = "description"; dropdownlist1.datavaluefield = "id"; dropdownlist1.databind();  

now i'm stuck.

now need set selectedvalue in list and/or define event onselectedindexchanged process user's selection

below example how did it:

<asp:dropdownlist id="ddlstatus" autopostback="true" runat="server" datasourceid="edslookstatus"     datavaluefield="cd"      datatextfield="lookupname"      onselectedindexchanged="ddlstatus_selectedindexchanged" /> <asp:textbox id="txtbxstatus" runat="server" text='<%# bind("status") %>' visible="false" /> 

here trick: added invisible textbox, linked "status". when ddl change value set new value txtbx:

protected void ddlstatus_selectedindexchanged(object sender, eventargs e) {     dropdownlist ddl = formviewclient.findcontrol("ddlstatus") dropdownlist;     textbox txtbx = formviewclient.findcontrol("txtbxstatus") textbox;     if (ddl != null && txtbx != null)     { txtbx.text = ddl.selectedvalue; } } 

to set selected value:

<asp:formview ... ondatabound="formviewclient_databound" > 

and

protected void formviewclient_databound(object sender, eventargs e) {     ...     dropdownlist ddl = formviewclient.findcontrol("ddlstatus") dropdownlist;     textbox txtbx = formviewclient.findcontrol("txtbxstatus") textbox;     if (ddl != null && txtbx != null)     { ddl.selectedvalue = txtbx.text; }     ... }