php - 我如何进行这个选择查询？

Question

我想在 mysql 中创建一个 SELECT 查询。

有两个表，users 和 image_info，需要选择以下列。

用户表:user_id、用户名、出生日期

图像信息:图像，图像路径

选择图像时。我只需要从 image_info 表中获取主图像。在 image_info 表中有一个列，例如:

image_type ENUM('primary', 'gallery') DEFAULT NULL,

这就是我尝试的方法..

$q = "SELECT u.user_id, u.username, u.dob, i.image, i.image_path
            FROM users u 
                INNER JOIN image_info i ON i.user_id = u.user_id
            WHERE u.sex = 'Male'
            ORDER BY u.date_registered DESC LIMIT 6";

但它无法正常工作以获得我的预期输出。

更新: 我的表输出..

mysql> select user_id, username, sex from users;
+---------+-------------+--------+
| user_id | username    | sex    |
+---------+-------------+--------+
|       1 | thara1234   | Male   |
|       2 | root234     | Male   |
|       3 | kamal123    | Female |
|       4 | Nilantha    | Male   |
|       5 | Ruwan324324 | Male   |
+---------+-------------+--------+
5 rows in set (0.00 sec)

mysql> select user_id, image, image_type from image_info;
+---------+----------------------------+------------+
| user_id | image                      | image_type |
+---------+----------------------------+------------+
|       2 | 2_root234_1433564588.jpg   | primary    |
|       1 | 1_thara1234_1433555104.jpg | primary    |
|       1 | 1_thara1234_1433556481.jpg | gallery    |
|       4 | 4_Nilantha_1433573768.jpg  | primary    |
+---------+----------------------------+------------+
4 rows in set (0.03 sec)

谢谢。

Answer 1

我认为，查询是:-

SELECT User.user_id, User.username, User.dob, Image.image, Image.image_path
FROM 
    users User LEFT JOIN image_info Image
    ON User.user_id = Image.user_id AND Image.image_type = 'PRIMARY'
WHERE User.sex= 'Male'
ORDER BY User.date_registered DESC LIMIT 6