Question

大家好我想尝试使用更高效的东西，而不是使用多个查询中的mysql_num_rows。我可以使用一个查询，例如mysql_num_rows()根据条件计算$type=="a"吗？并为b行，c行，d行等声明每个..的变量。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

Answer 2

可能是这样的:(如果没有主ID列）

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

或动态：

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

mysql_num_rows和条件

2 个答案: