【MySQL】字符串操作函数之length和char_length

  官网地址:https://dev.mysql.com/doc/refman/5.6/en/string-functions.html

  lenght:?https://dev.mysql.com/doc/refman/5.6/en/string-functions.html#function_length

  char_length:https://dev.mysql.com/doc/refman/5.6/en/string-functions.html#function_char-length

  Returns the length of the string?, measured in bytes. A multibyte character counts as multiple bytes. This means that for a string containing five 2-byte characters,?returns?, whereasreturns?.

  TheOpenGIS spatial function is namedin MySQL.

  Returns the length of the string?, measured in characters. A multibyte character counts as a single character. This means that for a string containing five 2-byte characters,returns?, whereasreturns?.

  需求计算表中某一个字段(string)的内容中某一个字符出现的次数

  说明:计算全部的长度然后减去字符A给转化后(就是删除掉落)全部的长度,这个差就是A的个数。这个我们要留心length和char_length处理的方法。当交换的字符A是一个字符串(AAAA),那就需求除于字符串的长度。

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