从数组OR逗号分隔的字符串：只在一个查询中从db获取字段

I have multiple numeric values which I can express as either an array, or as a comma-separated string. For each of these values I would like to select the corresponding database row. Is it possible to do this in one query?

// data examples
$array = array(3, 6, 200); // or more values
$string = '3,6,200' ; // or more values

I can do the following query for each value, to get a field from the table:

SELECT email FROM table WHERE id='$array_value';

But how can I get this in one query?

You should use IN operator. If $data is either array or comma separated list of numbers (string), do:

$in = is_array($data) ? implode(',', $data) : $data;
$query = "SELECT email FROM table WHERE id IN (" . $in . ")";

Only do this if you are sure that elements in the array are safe.

If you have to make your data safe you can do this

$in = is_array($data) ? 
        "'" . implode("','", array_map('mysql_real_escape_string', $data)) . "'" : 
        "'" . mysql_real_escape_string($data) . "'";

Or if you are expecting integer values, just go with:

$in = is_array($data) ? 
        implode(',', array_map('intval', $data)) : 
        (int)$data;

Try using IN.

$query = 'SELECT email FROM table WHERE id IN (' . ( is_array( $ids ) ? implode( ',', $ids ) : $ids ) . ')';

Assuming $ids is the list of IDs as either a string or an array.

// $vals is your "array or comma-separated string"
if( is_array($vals)) $vals = implode(",",$vals);
mysql_query( "SELECT `id`, `email` FROM `table` WHERE `id` IN (".$vals.")");

I selected id as well so that you can identify which email belongs to which ID when you loop through the results. If this is not important, you can drop it.