如何在 MySQL 中按相关性排序？
要按相关性排序，请使用case语句。为了理解这个概念，让我们创建一个表。创建表的查询如下-
mysql> create table OrderByRelevance -> ( -> UserId int, -> UserName varchar(200) -> );
现在您可以使用插入命令在表中插入一些记录。查询如下-
mysql> insert into OrderByRelevance values(101,'Carol Smith'); mysql> insert into OrderByRelevance values(102,'Carol Adams'); mysql> insert into OrderByRelevance values(103,'Carolnathan Todd'); mysql> insert into OrderByRelevance values(104,'John Smith'); mysql> insert into OrderByRelevance values(105,'Sam Carol Bond');
使用select语句显示表中的所有记录。查询如下-
mysql> select *from OrderByRelevance;输出结果
+--------+------------------+ | UserId | UserName | +--------+------------------+ | 101 | Carol Smith | | 102 | Carol Adams | | 103 | Carolnathan Todd | | 104 | John Smith | | 105 | Sam Carol Bond | +--------+------------------+ 5 rows in set (0.00 sec)
这是按相关性排序的查询。查询如下-
mysql> select max(UserId)as Id,UserName from OrderByRelevance -> where UserName like '%Carol%' group by UserName -> order by case when UserName like 'Carol%' THEN 0 -> WHEN UserName like '% %Carol% %' THEN 1 -> WHEN UserName like '%Carol' THEN 2 -> else 3 -> end,UserName;输出结果
+------+------------------+ | Id | UserName | +------+------------------+ | 102 | Carol Adams | | 101 | Carol Smith | | 103 | Carolnathan Todd | | 105 | Sam Carol Bond | +------+------------------+ 4 rows in set (0.00 sec)