how to run sql query on all column data and export result to csv -in c# -

i made sql queries on access db. in datagridview2 see in first column istalled programs in second how many computers installed program.

col1   col2 xxxx    1 yyyy    2 zzzz    3  oledbcommand command2 = new oledbcommand();             command2.connection = connection;             string query = "select item_1, count(item_1)    (select  item_1 audit_data category_id = 500)    group item_1 having (count(*)>0)   ";                     command2.commandtext = query;              oledbdataadapter da1 = new oledbdataadapter(command2);              da1.fill(dt2);             datagridview2.datasource = dt2;             datagridview2.autoresizecolumns(); 

the datagridview3 contains computers name programs installed when selection changed on datagridview2:

 string selcell = convert.tostring(datagridview2.currentcell.value);                oledbcommand command3 = new oledbcommand();             command3.connection = connection;             string query = "select distinct fully_qualified_domain_name audit_data, computer_master item_1= '"+selcell+"'    , category_id=500      , audit_data.computer_id = computer_master.computer_id     ";                   command3.commandtext = query;              oledbdataadapter da3 = new oledbdataadapter(command3);              da3.fill(dt3);             datagridview3.datasource = dt3;             datagridview3.autoresizecolumns(); 

and run these queries software installed computer names. don't know how run query on data on col 1 , export csv this.

xxxx; 1; qwer_pc yyyy; 2; asdf_pc;          qwer_pc zzzz; 3; asdf_pc;          qwer_pc;          yxcv_pc 

could solve problem? or can somehow combine 2 queries?

the solution easier thought:

select distinct item_1,fully_qualified_domain_name audit_data,computer_master category_id = 500      ,    audit_data.computer_id = computer_master.computer_id           

the csv export following :

     string csv = string.empty;  //add header row csv file. foreach (datagridviewcolumn column in datagridview4.columns) {     csv += column.headertext + ','; }  //add new line. csv += "\r\n";  //adding rows foreach (datagridviewrow row in datagridview4.rows) {     foreach (datagridviewcell cell in row.cells)     {         //add data rows.         csv += cell.value.tostring().replace(",", ";") + ',';     }      //add new line.     csv += "\r\n"; }  //exporting csv. string folderpath = txt_csv_exp_path.text; file.writealltext(folderpath +txt_exp_file_name.text +" .csv", csv);  messagebox.show("csv file saved.");