零基础带你学习MySQL—字符串相关的函数（十三）

川长思鸟来 2022-10-11 00:59 123阅读 0赞

## 零基础带你学习MySQL—字符串相关的函数（十三） ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70]

## 一、`CHARSET (str)`返回子串字符集 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 1]

## 二、`CONCAT`连接子串，将多个列拼接成一列 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 2]

## 三、`INSTR(string,substring)`返回`substring`在`string`中出现的位置 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 3]

## 四、`UCASE(string2)` 转换成大写 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 4]

## 五、`LCASE(string2)` 转换成小写 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 5]

## 六、`LEFT(string2,length)`表示从`string2`中的左边取`length`个字符 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 6]

## 七、`RIGHT(string2,length)`表示从`string2`中的右边取`length`个字符 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 7]

## 八、`LENGTH(string) string`长度\[按照字节\] ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 8]

## 九、`REPLACE (str,search_str,replace_str)` ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 9]

## 十、`STRCMP(string1,string2)`逐字比较两字串大小 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 10]

## 十一、`SUBSTRING(str,poisition,length)`从`str`的`position`开始【从1开始计算】，取length个字符 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 11]

## 十二、`LTRIM(string2)`去除前端空格 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 12]

## 十三、`RTRIM(string2)`去除后端空格 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 13]

## 十四、`TRIM(string)`去除前后端空格 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 14]

## 十六、练习 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 15]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70]: /images/20221005/c8880e43887c4ad3a533ac07620293fb.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 1]: /images/20221005/8cb8a43d2ae44e39b446ecbdac88d474.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 2]: /images/20221005/f0f632b2869b4123b4dd1fb1e1650441.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 3]: /images/20221005/9fd1592a7f6e49c386f7e087a59008c7.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 4]: /images/20221005/de4bbb783467438c9fe8db5d7bc1464c.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 5]: /images/20221005/ac446ef378c04125acb6ccec8c289879.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 6]: /images/20221005/083ed0e19e4e460593752105a6c6385d.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 7]: /images/20221005/6c70f1b3335e480bbd3ef82d4c87bcd2.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 8]: /images/20221005/5743bd977f554c4fa763e0ae106e407c.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 9]: /images/20221005/a995922362f645f2a6bef0b4a8ffc0b1.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 10]: /images/20221005/2b41eed80a2649a588c03b178152f6f0.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 11]: /images/20221005/8e4b61ea119144f88c7f7fd3072da8c1.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 12]: /images/20221005/5218ab57940a490d88b51c22a8c044e7.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 13]: /images/20221005/95f56a8a018845b6abebfa014caac438.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 14]: /images/20221005/b1f1962d0dd44b4bb77c5218f4afcc5f.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L20wXzQ2Mzc0OTY5_size_16_color_FFFFFF_t_70 15]: /images/20221005/a596a597fff6409f909d80b69d68a69c.png