Question

存在以下表格：

+----------------------+
| Tables_in_automobile |
+----------------------+
| car has options      |
| car sold             |
| company              |
| customer             |
| members              |
| model                |
| model has options    |
| options              |
+----------------------+

MariaDB [automobile]> describe model;
+-----------------+--------------+------+-----+---------+-------+
| Field           | Type         | Null | Key | Default | Extra |
+-----------------+--------------+------+-----+---------+-------+
| company name    | varchar(100) | NO   | PRI | NULL    |       |
| model name      | varchar(100) | NO   | PRI | NULL    |       |
| number of seats | int(10)      | NO   |     | NULL    |       |
| cost            | int(10)      | NO   |     | NULL    |       |
+-----------------+--------------+------+-----+---------+-------+

MariaDB [automobile]> describe options;
+-------------+--------------+------+-----+---------+----------------+
| Field       | Type         | Null | Key | Default | Extra          |
+-------------+--------------+------+-----+---------+----------------+
| id          | int(11)      | NO   | PRI | NULL    | auto_increment |
| option name | varchar(100) | NO   |     | NULL    |                |
| cost        | int(10)      | NO   |     | NULL    |                |
+-------------+--------------+------+-----+---------+----------------+

MariaDB [automobile]> describe `model has options`;
+--------------+--------------+------+-----+---------+-------+
| Field        | Type         | Null | Key | Default | Extra |
+--------------+--------------+------+-----+---------+-------+
| company name | varchar(100) | NO   | MUL | NULL    |       |
| model name   | varchar(100) | NO   |     | NULL    |       |
| option id    | int(10)      | YES  | MUL | NULL    |       |
+--------------+--------------+------+-----+---------+-------+

我需要找到满足以下要求的特定车型：

座位数＆gt; =某个值
该车配有一套选项

以下查询满足第一个条件，但是如果任何汽车有任何一个或多个 通过查询提供的选项 ，它包含在结果中。我只需要那些提供了确切选项的汽车：

SELECT `company name`, `model name`, `number of seats`, 
    SUM(`options`.`cost`)+`model`.`cost` AS 'cost' 
FROM `model` NATURAL JOIN `model has options` JOIN `options` 
WHERE `model has options`.`option id` = `options`.`id` 
    AND `number of seats`>=3 
    AND `option id` IN (3,4,7) 
GROUP BY `company name`, `model name` 
ORDER BY `cost`

Answer 1

HAVING子句可用于确保不同匹配选项的数量等于所提供选项的数量。

SELECT `company name`, `model name`, `number of seats`, 
    SUM(`options`.`cost`)+`model`.`cost` AS 'cost' 
FROM `model` NATURAL JOIN `model has options` JOIN `options` 
WHERE `model has options`.`option id` = `options`.`id` 
    AND `number of seats`>=3 
    AND `option id` IN (3,4,7) 
GROUP BY `company name`, `model name` 
HAVING COUNT(DISTINCT (`option id`)) = 3
ORDER BY `cost`

Answer 2

另一种方法

SELECT Field FROM model
    WHERE FIND_IN_SET(Field, "company name,model name,number of seats") = 0;

这样的东西会找到不在该数组中的任何Field值。返回空集表示已找到所有。另一种方法是SELECT COUNT(*) FROM ...

限制：由于逗号用作分隔符，因此数组中的任何项都不能使用逗号。

如何检查列中的值是否都属于数组？

2 个答案: