php - mysql_num_rows 和条件

Question

大家好，我正在尝试使用更高效的方法，而不是使用来自多个查询的 mysql_num_rows。我是否可以使用一个查询，例如根据条件 if $type=="a" 计算 mysql_num_rows()？并为每个.. b 行、c 行、d 行等声明变量。谢谢

$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