MySQL搜索好友查询

Question

我有一个用户表：

user_id | firstname | last name | picUrl ...
    1        bob       smith       null  
    2        bobby     smith       null  
    3        rob       smithies    null  

我也有一个朋友表：

friend1_id | friend2_id | status | date_established
      1          2        accepted   2018-02-06 10:23:01
      2          1        accepted   2018-02-06 10:23:01

我有一个简单的查询，可以根据条件（$ searchString）搜索用户，并根据“最佳”匹配对它们进行排序：

$query = "SELECT user_id, firstname, lastname, picUrl, LOWER(CONCAT(firstname, ' ', lastname)) as fullname  
          FROM user
          WHERE LOWER(CONCAT(firstname, ' ', lastname)) LIKE LOWER('%" . $searchString . "%') AND user_id != '{$userId}'
          ORDER BY
             CASE WHEN fullname = LOWER('" . $searchString . "') THEN 0
                  WHEN fullname = LOWER('" . $searchString . "%') THEN 1
                  WHEN fullname = LOWER('%" . $searchString . "%') THEN 2
                  WHEN fullname = LOWER('%" . $searchString . "') THEN 3
                  ELSE 4
                END, fullname DESC
          LIMIT 5";

该查询将忽略当前用户：

user_id != '{$userId}'

因为您无法将自己加为好友。

如何忽略/不显示已经是朋友的用户？

例

我是用户1。

我搜索“史密斯”。

=>我是用户1，所以没有显示。

=>用户2已经是我的朋友，因此不显示。

=>将显示Just Rob Smithies 。

Answer 1

只需再添加一个与朋友的ID相匹配的条件即可。 如下更改查询

$query = "SELECT user_id, firstname, lastname, picUrl, LOWER(CONCAT(firstname, ' ', lastname)) as fullname  
          FROM user
          WHERE LOWER(CONCAT(firstname, ' ', lastname)) LIKE LOWER('%" . $searchString . "%') AND (user_id != '{$userId}' AND user_id not in (SELECT friend1_id from friends where friend2_id = '{$userId}') AND user_id not in (SELECT friend2_id from friends where friend1_id = '{$userId}'))
          ORDER BY
             CASE WHEN fullname = LOWER('" . $searchString . "') THEN 0
                  WHEN fullname = LOWER('" . $searchString . "%') THEN 1
                  WHEN fullname = LOWER('%" . $searchString . "%') THEN 2
                  WHEN fullname = LOWER('%" . $searchString . "') THEN 3
                  ELSE 4
                END, fullname DESC
          LIMIT 5";