MySQL 运算符 SELECT 如何从相似的行中获得一个确切的行结果?

问题描述

我在简单的表格中有这样的SEO"行类别(id、名称、seo):

i have such 'SEO' rows in simple table categories (id, name, seo):

"abc"
"abc 22"
"abc 33"

在 MySQL 中如何使用这个查询

how in MySQL get with this query

SELECT id FROM categories WHERE seo='abc' AND LENGTH('abc')='3';"

没有找到abc 22"和abc 33"的abc"的精确行结果abc"?

one exact row result "abc" from "abc" without finding "abc 22" and "abc 33"?

推荐答案

create table stuff
(   id int auto_increment primary key,
    seo varchar(100) not null
    -- unique key (seo) not a bad idea
);

insert stuff (seo) values ('abc'),('abc7'),('kitty likes abc'),('abc and more abc'),('kittens');
insert stuff (seo) values ('abc at beginning'),('frogs'),('and at the end abc'),('qwertyabcqwerty');


select id from stuff where seo='abc';
+----+
| id |
+----+
|  1 |
+----+
1 row in set (0.02 sec)

以下是 like 的行为:

select * from stuff where seo like '%abc';
+----+--------------------+
| id | seo                |
+----+--------------------+
|  1 | abc                |
|  3 | kitty likes abc    |
|  4 | abc and more abc   |
|  8 | and at the end abc |
+----+--------------------+
4 rows in set (0.00 sec)

select * from stuff where seo like 'abc%';
+----+------------------+
| id | seo              |
+----+------------------+
|  1 | abc              |
|  2 | abc7             |
|  4 | abc and more abc |
|  6 | abc at beginning |
+----+------------------+
4 rows in set (0.00 sec)

select id,seo from stuff where seo like '%abc%';
+----+--------------------+
| id | seo                |
+----+--------------------+
|  1 | abc                |
|  2 | abc7               |
|  3 | kitty likes abc    |
|  4 | abc and more abc   |
|  6 | abc at beginning   |
|  8 | and at the end abc |
|  9 | qwertyabcqwerty    |
+----+--------------------+
7 rows in set (0.00 sec)

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