php - Array in Where clause -

how can insert array clause? first query id:

$query = "select id #_categories alias = 'agenda'"; $result = mysql_query($query) or die(mysql_error());    while($linha = mysql_fetch_array($result)){    $vnome = $linha['id'];  } 

now second query final result:

$query = "select introtext $tabela catid in ($vnome) <> ''"; 

and result is:

select introtext #_content catid in (36) <> '' 

why can't put ids in clause in?

ps: sorry bad english, not native language.

$vnome=array(); $result = mysql_query($query) or die(mysql_error());   while($linha = mysql_fetch_array($result)){   $vnome[] = $linha['id'];  } 

then sql:

$query = "select introtext $tabela catid in (".implode(",",$vnome).")";