MySQL中的各种函数

短命女 2023-06-17 14:58 18阅读 0赞

数据库：own ->>表：aiqiyi

1.去除数据左右空格：trim()

说明：去除actors列中的左右空格。

select actors,trim(actors) as c1 from aiqiyi limit 20;

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjgzMDY5Nw_size_16_color_FFFFFF_t_70][]

2.去除数据左空格：ltrim()

3.去除数据右空格：rtrim()

4.返回文本串左边的字符：left()

说明：返回文本左边的第一个字符

select actors,left(actors,1) as c1 from aiqiyi limit 20;

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjgzMDY5Nw_size_16_color_FFFFFF_t_70 1][]

说明：返回文本串的前三个字符

select actors,left(actors,3) as c1 from aiqiyi limit 20;

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjgzMDY5Nw_size_16_color_FFFFFF_t_70 2][]

5.返回文本串的长度：length()

说明：返回actors的长度

select actors,length(actors) as c1 from aiqiyi limit 20;

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjgzMDY5Nw_size_16_color_FFFFFF_t_70 3][]

6.返回子串在文本串中的位置：locate()

说明：在actors列查找“吕”字的位置。

select actors,locate('吕',actors) as c1 from aiqiyi limit 20;

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjgzMDY5Nw_size_16_color_FFFFFF_t_70 4][]

7.将字符串变为小写：lower()

8.返回右边的字符串：right()

说明：返回actors右边的三个字符

select actors,right(actors,3) as c1 from aiqiyi limit 20;

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjgzMDY5Nw_size_16_color_FFFFFF_t_70 5][]

9.返回字符串的大写形式：upper()

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