Question

如何使用PHP从下面的查询MySQL查询中获取计数值。

这是我的MySQL代码。

$dbc = mysqli_query($mysqli,"SELECT COUNT(*) FROM((SELECT users_friends.id
                            FROM users_friends
                            INNER JOIN users ON users_friends.user_id = users.user_id
                            WHERE users_friends.user_id = 1 
                            AND users_friends.friendship_status = '1')
                            UNION
                            (SELECT users_friends.id
                            FROM users_friends
                            INNER JOIN users ON users_friends.friend_id = users.user_id
                            WHERE users_friends.friend_id = 1
                            AND users_friends.friendship_status = '1')) as friends");

Answer 1

使用SQL_CALC_FOUND_ROWS应该简化：

$dbc = mysqli_query($mysqli,"SELECT SQL_CALC_FOUND_ROWS users_friends.id
                        FROM users_friends
                        INNER JOIN users ON users_friends.user_id = users.user_id
                        WHERE users_friends.user_id = 1 
                        AND users_friends.friendship_status = '1'
                       ");

然后再做

$rs = mysqli_query($mysqli, "SELECT FOUND_ROWS()"));
$rec = $rs->fetch_array();
$count = $rec[0];

此方法将返回与查询匹配的记录数，忽略任何LIMIT语句，而使用$rs->num_rows将仅提供实际返回的记录数。取决于你想要的那个。

Answer 2

if ($result = mysqli_query($link, "SELECT Name FROM City LIMIT 10")) {
    printf("Select returned %d rows.\n", mysqli_num_rows($result));

    /* free result set */
    mysqli_free_result($result);

http://us.php.net/manual/en/mysqli.query.php

Answer 3

假设您已正确连接到MySQL服务器并且查询正确执行，您可以使用以下代码：

$values = mysql_fetch_row($dbc);
$count = $values[0];

Answer 4

您的查询看起来应该像SELECT numThings FROM xxx

一样SELECT COUNT（*）

您将在PHP中引用numThings：

$result = mysql_query("SELECT COUNT(*) as `numThings` FROM xxx");
$row = mysql_fetch_assoc($result);
$count = $row['numThings'];

PHP编码问题

4 个答案: