MySQL 寻常str函数
发布时间：2022-07-08 20:30:09 所属栏目：MySql教程 来源：互联网
导读：MySQL常见的字符串函数 整理自官档。 1.1 SUBSTR or SUBSTRING SUBSTR(str,pos), SUBSTR(str FROM pos),SUBSTR(str,pos,len), SUBSTR(str FROM pos FOR len) SUBSTR() is a synonym for SUBSTRING(). SUBSTRING(str FROM pos FOR len) The forms without a l
|
MySQL常见的字符串函数 整理自官档。 1.1 SUBSTR or SUBSTRING SUBSTR(str,pos), SUBSTR(str FROM pos),SUBSTR(str,pos,len), SUBSTR(str FROM pos FOR len) SUBSTR() is a synonym for SUBSTRING(). SUBSTRING(str FROM pos FOR len) The forms without a len argument return asubstring from string str starting at position pos. The forms with a len argument return asubstring len characters long from string str, starting at position pos. The forms that use FROM arestandard SQL syntax. It is also possible to use a negative value for pos. In this case, the beginningof the substring is pos characters from the end of the string, rather than the beginning. Anegative value may be used for pos in any of the forms of this function. For all forms of SUBSTRING(), the positionof the first character in the string from which the substring is to be extracted is reckoned as1. mysql> SELECTSUBSTRING('Quadratically',5); -> 'ratically' mysql> SELECT SUBSTRING('foobarbar' FROM4); -> 'barbar' mysql> SELECTSUBSTRING('Quadratically',5,6); -> 'ratica' mysql> SELECT SUBSTRING('Sakila', -3); -> 'ila' mysql> SELECT SUBSTRING('Sakila', -5,3); -> 'aki' mysql> SELECT SUBSTRING('Sakila' FROM -4FOR 2); -> 'ki' This function is multibyte safe. If len is less than 1,the result is the empty string. 1.2 LENGTH LENGTH(str) 返回字节数 Returns the length of the string str,measured in bytes. A multibyte character counts as multiple bytes. This means that for a stringcontaining five 2-byte characters, LENGTH() returns 10, whereas CHAR_LENGTH() returns 5. mysql> SELECT LENGTH('text'); （编辑：衡阳站长网） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
站长推荐
热点阅读