如何使用PHP增加MySQL数据库中的某些行 - How do you increment certain rows in a MySQL database with PHP?

How do you increment certain rows in a MySQL database with PHP?

我有这个PHP:

$adj_index = $currentSignup + 1 - $r;//$r=3 and $currentSignup=24
for($i=1; $i<$referrals; $i++){
    $current_index = $currentSignup + 1 - $i;
    $q = "SELECT signup_id FROM app_sign_ups WHERE (adjusted_index='$current_index' AND app_id='$app_id')";
    $r = mysqli_query ($dbc, $q) or trigger_error("Query: $q'n<br />MySQL Error: " . mysqli_error($dbc));
    $next_index = $current_index + 1;
    if (mysqli_num_rows($r) == 1){
        $row = mysqli_fetch_array($r, MYSQLI_ASSOC);
        $signuper = $row['signup_id'];
        $q = "UPDATE app_sign_ups SET adjusted_index='$next_index' WHERE (app_id='$app_id' AND signup_id='$signuper')";
        $r = mysqli_query ($dbc, $q) or trigger_error("Query: $q'n<br />MySQL Error: " . mysqli_error($dbc));
    }
}
$q = "UPDATE app_sign_ups SET adjusted_index='$adj_index' WHERE app_s_id='$app_s_id'";
$r = mysqli_query ($dbc, $q) or trigger_error("Query: $q'n<br />MySQL Error: " . mysqli_error($dbc));

它应该在我的数据库中更新行。每一行都有一个从1到25的值(adjusted_index)。有了它，我将数字25变为22(通过从原始数字[25]中删除$r)，并将之前的22-24分别移动一个(因此到23,24,25)。由于某些原因，当我运行它的时候结果是22 24 25 22而不是我想要的23 24 25 22。我已经在其他几个组合上完成了它，似乎有adjusted_index的行被最后一行取代(22被25取代)。

只运行一条UPDATE语句，一次:

$q = " UPDATE app_sign_ups 
       SET adjusted_index = adjusted_index 
                          + CASE WHEN adjusted_index < 25
                                 THEN 1
                                 ELSE - '$r' 
                            END  
       WHERE adjusted_index >= 25 - '$r' 
         AND app_id = '$app_id'
       ORDER BY adjusted_index 
     ";

或者，更好的是，使用2个UPDATE语句:

$q1 = " UPDATE app_sign_ups 
        SET adjusted_index = adjusted_index + 1
        WHERE adjusted_index >= 25 - '$r' 
          AND app_id = '$app_id'
        ORDER BY adjusted_index DESC              --- this line is needed if
     ";                                           --- you have a UNIQUE index on
                                                  --- (app_id, adjusted_index)
$q2 = " UPDATE app_sign_ups 
        SET adjusted_index = 25 - '$r'
        WHERE adjusted_index = 26 
          AND app_id = '$app_id'
     ";