Question

我使用sql获取text值，并将text字符串转换为整数以比较相同的指定数字。原谅我可怜的英语。第1步，我使用这个sql get text值。（结果是'8000mAh'，'2000mAh'）

SELECT `product_id`, `text` 
FROM `jfw_product_attribute` 
WHERE `attribute_id` =3

步骤2，我使用sql convert text string to integer来比较相同的指定数字:(我删除最后三个str'mAh'）

SELECT `product_id` ,
CASE
WHEN cast( REVERSE( SUBSTRING( REVERSE( text ) , 4 ) ) as  UNSIGNED int) <1000
THEN 1
WHEN 1000 <= cast( REVERSE( SUBSTRING( REVERSE( text ) , 4 ) ) as  UNSIGNED int) <=2000
THEN 2
WHEN 2001 <= cast( REVERSE( SUBSTRING( REVERSE( text ) , 4 ) ) as  UNSIGNED int) <=3000
THEN 3
WHEN 3001 <= cast( REVERSE( SUBSTRING( REVERSE( text ) , 4 ) ) as  UNSIGNED int) <=4000
THEN 4
WHEN 4001 <= cast( REVERSE( SUBSTRING( REVERSE( text ) , 4 ) ) as  UNSIGNED int) <=5000
THEN 5
WHEN 5001 <= cast( REVERSE( SUBSTRING( REVERSE( text ) , 4 ) ) as  UNSIGNED int) <=8000
THEN 6
WHEN 8001 <= cast( REVERSE( SUBSTRING( REVERSE( text ) , 4 ) ) as  UNSIGNED int)
THEN 7
END AS `filter_id`
FROM `jfw_product_attribute`
WHERE `attribute_id` =3

我不能正确filter_id，我只是得到所有filter_id是2.有人可以帮助我吗？非常感谢你。

Answer 1

您可以执行以下操作，因为case语句将与第一个可能的过滤器匹配，因此您需要做的就是根据<=进行匹配

SELECT `product_id` ,
CASE
WHEN cast( REVERSE( SUBSTRING( REVERSE( text ) , 4 ) ) as  UNSIGNED int) <1000
THEN 1
WHEN cast( REVERSE( SUBSTRING( REVERSE( text ) , 4 ) ) as  UNSIGNED int) <=2000
THEN 2
WHEN cast( REVERSE( SUBSTRING( REVERSE( text ) , 4 ) ) as  UNSIGNED int) <=3000
THEN 3
WHEN cast( REVERSE( SUBSTRING( REVERSE( text ) , 4 ) ) as  UNSIGNED int) <=4000
THEN 4
WHEN cast( REVERSE( SUBSTRING( REVERSE( text ) , 4 ) ) as  UNSIGNED int) <=5000
THEN 5
WHEN cast( REVERSE( SUBSTRING( REVERSE( text ) , 4 ) ) as  UNSIGNED int) <=8000
THEN 6
WHEN 8001 <= cast( REVERSE( SUBSTRING( REVERSE( text ) , 4 ) ) as  UNSIGNED int)
THEN 7
END AS `filter_id`
FROM `jfw_product_attribute`
WHERE `attribute_id` =3

Answer 2

我只是简单地将text投射到一个数字上;实际上，在数字上下文中使用它将隐式地执行此操作。因此，人们可以这样做：

SELECT product_id, text DIV 1000 + 1 AS filter_id
FROM   jfw_product_attribute
WHERE  attribute_id = 3

但请注意，这不会使完全产生与原始CASE声明所预期相同的结果：

它以不同方式处理端点（即等于2000的值将产生3而不是2）;以及
它将每千个视为不同的间隔，而最初汇总的是5001-8000和8001+。

那就是说，通过采用这种方法来实现你想要的东西应该是微不足道的。

如何将字符串转换为整数并比较指定数字使用mysql？

2 个答案: