[英]MySQL: how to make an order on select by giving specific score to special records
我有一个简单的表,例如:
id | name | category
------------------------
1 | banana | 1
2 | orange | 1
3 | fruit | 1
4 | potato | 2
5 | car | 0
我有很多特殊的过滤器,应该为列表显示分配特殊的分数。 这是此示例的机制:
所以在我的结果中,我需要
id | name | category | score
-------------------------------
1 | banana | 1 | 3 ( condition 1+4)
2 | orange | 1 | 3 ( condition 1+4)
3 | fruit | 1 | 2 ( condition 2+4)
4 | potato | 2 | 1 ( condition 3+4)
5 | car | 0 | 0 ( no match)
最后,我想按分数排序结果。 我无法创建新列,因为条件是由用户选择的。 什么是MySQL查询?
一种可能的方法:
SELECT id, name, category,
IF(category > 0, 1, 0) +
(CASE name WHEN 'banana' THEN 2
WHEN 'orange' THEN 2
WHEN 'fruit' THEN 1
ELSE 0 END)
AS score
FROM ttt
ORDER BY score DESC
你可以这样做:
SELECT
id,
name,
category,
nameCondition + catCondition AS Score
FROM
(
SELECT
id, name, category,
CASE
WHEN name IN ('banana', 'orange') THEN 2
WHEN name = 'fruit' THEN 1
WHEN name = 'potato' THEN 0
ELSE 0
END AS nameCondition,
CASE
WHEN category > 0 THEN 1
ELSE 0
END AS catCondition
FROM tablename
) AS t;
SQL提琴演示 。
这将为您提供:
| ID | NAME | CATEGORY | SCORE |
----------------------------------
| 1 | banana | 1 | 3 |
| 2 | orange | 1 | 3 |
| 3 | fruit | 1 | 2 |
| 4 | potato | 2 | 1 |
| 5 | car | 0 | 0 |
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