mysql - 区分大小写的字符串出现

Question

我正在使用以下查询来拆分列值。它适用于不区分大小写的情况，但我希望它能够区分大小写。

例如，在字符串 'Oil is a product Ingredients are' 中，如果我的搜索关键字是 'ingredients'，它应该返回 false 并且应该只返回 true 如果搜索关键字是“成分”。 mysql 中是否有任何函数允许这样做？

SELECT 
  SUBSTRING_INDEX(description, 'Ingredients', 1),
    if(LOCATE('Ingredients', description)>0, SUBSTRING_INDEX(description, 'Ingredients', -1), '')
FROM `product`

Answer 1

来自mysql的文档LOCATE 功能:

This function is multibyte safe, and is case-sensitive only if at least one argument is a binary string.

也就是说，您需要cast/convert您的参数以执行区分大小写的匹配。

例如:如果您的第一条记录是Oil is a product Ingredients are...，您的第二条记录是Oil is a product ingredients are.. . 然后是以下查询:

SELECT 
  LOCATE('ingredients', description) AS match_both_1,
  LOCATE('Ingredients', description) AS match_both_2,
  LOCATE(CAST('ingredients' AS BINARY), CAST(description AS BINARY)) AS match_second,
  LOCATE(CAST('Ingredients' AS BINARY), CAST(description AS BINARY)) AS match_first
FROM product

会给你预期的结果:

| match_both_1 | match_both_2 | match_second | match_first |
|     18       |     18       |      0       |     18      |
|     18       |     18       |     18       |      0      |

参见 DEMO .