mysql_num_rows和条件

Question

Hi guys I am trying to use something more efficient instead of using mysql_num_rows from multiple queries. Am I able to use one query and for example count mysql_num_rows() based on condition if $type=="a" ? And declare variable for each.. for b rows, c rows, d rows etc. Thank you

$rows_a = mysql_query("SELECT $type FROM table WHERE $type = 'a'");
$a_rows = mysql_num_rows($rows_a);

$rows_b = mysql_query("SELECT $type FROM table WHERE $type = 'b'");
$b_rows = mysql_num_rows($rows_b);

$rows_c = mysql_query("SELECT $type FROM table WHERE $type = 'c'");
$c_rows = mysql_num_rows($rows_c);

$rows_d = mysql_query("SELECT $type FROM table WHERE $type = 'd'");
$d_rows = mysql_num_rows($rows_d);

Answer 1

SELECT COUNT(id), type FROM table GROUP BY type

Answer 2

Could be like this : ( if no primary ID column)

SELECT COUNT(*) as num_rows, type FROM table WHERE type IN ('a', 'b', 'c', 'd') GROUP BY type 

or dynamic :

SELECT COUNT(*) as num_rows, type FROM table WHERE type IN ('select types from a sub query') GROUP BY type