2014.09.23 mysql 一条sql语句实现实现搜索功能（加权排序）

一、加权排序原理

二、转化为SQL语句(合理使用case when xx then x else x end 等mysql的函数)

SELECT
1 * (
document.w10 + document.w20 + document.w30
) * (
document.w11 + document.w21 + document.w31
) AS w,
document.*
FROM
(
SELECT
0,
CASE WHEN d.abstracts LIKE '%1%' THEN
2 ELSE 0.1
END AS w10,
CASE WHEN d.tags LIKE '%1%' THEN
3 ELSE 0.1
END AS w20,
CASE WHEN d. NAME LIKE '%1%' THEN
4 ELSE 0.1
END AS w30,
CASE WHEN d.abstracts LIKE '%2%' THEN
2 ELSE 0.1
END AS w11,
CASE WHEN d.tags LIKE '%2%' THEN
3 ELSE 0.1
END AS w21,
CASE WHEN d. NAME LIKE '%2%' THEN
4 ELSE 0.1
END AS w31,
d.*
FROM
document d
) document LEFT JOIN document dd
ON document.id = dd.id
WHERE
dd.sts = 'normal'
AND to_days(now()) >= to_days(dd.protect_time)
AND dd.create_time >= '2014-07-10 00:00:00'
AND dd.create_time <= '2014-09-23 09:13:56'
AND dd.category_id LIKE '0001%'
AND dd.p_id LIKE '%'
HAVING w > 0.09
ORDER BY
w DESC,
dd.create_time DESC