从 select count MySQL 语句获取行数

Question

$How_Many_Manufacturers = "SELECT COUNT(manufacturer), manufacturer
                                   FROM products
                                   WHERE name LIKE '%$new_title%'
                                   GROUP BY manufacturer";


        $result2 = mysql_query($How_Many_Manufacturers, $connection) or die(mysql_error());

$num_rows = mysql_num_rows($result2);

if ($num_rows == 0)
{
    echo "<div id=\"noMatches\">No Matches</div>";
                                                   }

else {

                                                   }

if 语句将不起作用。 我该如何更正这个脚本？

Answer 1

@Arjan你的SQL语法有错误；检查与您的 MySQL 服务器版本相对应的手册，了解在第 4 行“-25,25”附近使用的正确语法 -RPM

确保在查询中转义 $new_title。

$How_Many_Manufacturers = "SELECT COUNT(manufacturer), manufacturer
                               FROM products
                               WHERE name LIKE '%".mysql_real_escape_string($new_title)."%'
                               GROUP BY manufacturer";

Answer 2

SELECT COUNT 将始终返回一行（即使计数为零）。只需删除 COUNT，或获取行即可查看计数。