I currently am using this query to select "profile_picture from the column relation and table media, although I noticed my return default.png inside my html image tag doesn't work for results. Is there any way I could return: IF error
我目前正在使用此查询从列关系和表媒体中选择“profile_picture,虽然我注意到我的html图像标记内的return default.png对结果不起作用。有什么方法可以返回:IF错误
"SELECT * FROM media WHERE post_id = '5552773e65a2b' AND relation = 'profile_picture"
My current query
我目前的查询
"SELECT * FROM media WHERE userID = $friend->user_id AND relation = 'profile_picture' ORDER BY id DESC LIMIT 1"
1 个解决方案
#1
While this would probably be easier to handle with your scripting language, you could do a union all to get the default value since you're ordering by the id field:
虽然使用脚本语言可能更容易处理,但您可以使用union all来获取默认值,因为您按id字段进行排序:
SELECT id, picture
FROM media
WHERE userID = $friend->user_id
AND relation = 'profile_picture'
UNION ALL
SELECT -1 id, 'default.png' picture
ORDER BY id DESC LIMIT 1
- SQL Fiddle Demo
SQL小提琴演示
#1
While this would probably be easier to handle with your scripting language, you could do a union all to get the default value since you're ordering by the id field:
虽然使用脚本语言可能更容易处理,但您可以使用union all来获取默认值,因为您按id字段进行排序:
SELECT id, picture
FROM media
WHERE userID = $friend->user_id
AND relation = 'profile_picture'
UNION ALL
SELECT -1 id, 'default.png' picture
ORDER BY id DESC LIMIT 1
- SQL Fiddle Demo
SQL小提琴演示