Question

Peter通过单击Michelle页面上的“添加朋友”按钮向数据库发送请求，数据库表tbl_frienRequest将Peter存储在“user”，并将Michelle存储在“targetuser”。

当米歇尔访问彼得的页面时，彼得的页面不得显示“添加朋友”按钮。当彼得访问米歇尔页面时，米歇尔的页面也不得显示“添加朋友”按钮。

如何编写if else语句以显示或不显示其页面上的“添加朋友”按钮？目前我正在使用这种方法：

    $query111 = "SELECT id FROM tbl_frienRequest WHERE user='{$username1}' AND targetuser='{$username2}'";
    $result111 = mysql_query($query111,$connection) or die (mysql_error());
    confirm_query($result111);
    $requestCount = mysql_num_rows($result111);

    $query2 = "SELECT id FROM tbl_frienRequest WHERE user='{$username2}' AND targetuser='{$username1}'";
    $result2 = mysql_query($query2,$connection) or die (mysql_error());
    confirm_query($result2);
    $requestCount2 = mysql_num_rows($result2);

if (($requestCount == 0) or ($requestCount2 == 0)){
    //show "add friend" button.
}

我认为它有效，但代码很长，有没有其他缩短代码来获得相同的输出？

Answer 1

$query111 = "SELECT id FROM tbl_frienRequest WHERE user in('{$username1}','{$username2}') AND targetuser in ('{$username2}','{$username2}' )";

Answer 2

您可以在查询中使用OR条件：即：

SELECT id
FROM tbl_frienRequest
WHERE (USER='{$username1}'
       AND targetuser='{$username2}')
  OR ( USER='{$username2}'
  AND targetuser='{$username1}'

试试这个：

$query111 = "SELECT id FROM tbl_frienRequest WHERE (user='{$username1}' AND targetuser='{$username2}') OR ( user='{$username2}' AND targetuser='{$username1}')";
$result111 = mysql_query($query111,$connection) or die (mysql_error());
confirm_query($result111);
$requestCount = mysql_num_rows($result111);
if ($requestCount == 0){
            //show "add friend" button.
}

Answer 3

$query111 = "SELECT id FROM tbl_frienRequest WHERE (user='{$username1}' 
AND targetuser='{$username2}') 
OR user='{$username2}' AND targetuser='{$username1}'";

Answer 4

我不确定我完全理解;你只想要一个会返回两个选项的查询？试试这个：

$sql = "SELECT id FROM tbl_frienRequest
            WHERE (user='{$username1}' AND targetuser='{$username2}')
              OR
                  (user='{$username2}' AND targetuser='{$username1}')";

这将返回两个选项;唯一的潜在技巧是找出哪个是哪个（如果两个都返回结果）。

Answer 5

 $query = "SELECT id FROM tbl_frienRequest WHERE user='{$username1}' AND targetuser='{$username2}' OR user='{$username2}' AND targetuser='{$username1}' " ;

AND优先于OR，因此您将通过此一个查询获得所需的结果

如何将2个mysql语句组合成1个？

5 个答案: