如何在 MySQL 中按相关性排序?
mysqlmysqli database
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) -> ); Query OK, 0 rows affected (0.51 sec)
现在，您可以使用 insert 命令在表中插入一些记录。查询如下 −
mysql> insert into OrderByRelevance values(101,'Carol Smith'); Query OK, 1 row affected (0.18 sec) mysql> insert into OrderByRelevance values(102,'Carol Adams'); Query OK, 1 row affected (0.17 sec) mysql> insert into OrderByRelevance values(103,'Carolnathan Todd'); Query OK, 1 row affected (0.33 sec) mysql> insert into OrderByRelevance values(104,'John Smith'); Query OK, 1 row affected (0.22 sec) mysql> insert into OrderByRelevance values(105,'Sam Carol Bond'); Query OK, 1 row affected (0.12 sec)
使用 select 语句显示表中的所有记录。查询如下 −
mysql> select *from OrderByRelevance;
输出
+--------+------------------+ | 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
+------+------------------+ | Id | UserName | +------+------------------+ | 102 | Carol Adams | | 101 | Carol Smith | | 103 | Carolnathan Todd | | 105 | Sam Carol Bond | +------+------------------+ 4 rows in set (0.00 sec)
