PHP连接和区分？

I am using this code to get id from database:

$selected_event_ids .= $get_event_id; 

and the coming output is:1149

but we want the output like: 11,4,9

try this

for() { // in loop
    $selected_event_ids[] = $get_event_id;
}

echo implode(',',$selected_event_ids);

it should be:

while($get_event_id = mysql_fetch_array($query)){
    $selected_event_ids[] = $get_event_id['row_name'];
}

echo implode(',',$selected_event_ids);

try this

$selected_event_ids .= $get_event_id.","; 

you will have output like 11,4,9,

then you need to truncate the last extra comma with this

$selected_event_ids = substr($selected_event_ids,0,strlen($selected_event_ids)-1);