substring(string [from] [for]) 函数用于提取从位置 from 开始的 for 个字符子串,位置从 1 开始计算。substr(string, from [, count]) 的作用相同。 SELECT substring('Thomas' from 2 for 3), substr('Thomas',2, 3); | substring | substr | |---|---| | hom | hom | left(str, n) 函数...
substring(string [FROM] [for])函数用于提取从位置FROM开始的for个字符子串,位置从1开始计算。substr(string, FROM[, count])的作用相同。 SELECTsubstring('nihao'FROM2for3),--ihasubstr('xiaofeng',2,3);--iao translate(string , FROM, to)函数将字符串string中出现在FROM中的字符串替换成to中相应位置的...
Introduction to PostgreSQL SUBSTRING() function TheSUBSTRING()function allows you to extract a substring from a string and return the substring. Here’s the basic syntax of theSUBSTRING()function: SUBSTRING(string,start_position,length) In this syntax: ...
PostgreSQL SUBSTRING() function with Example : The PostgreSQL substring function is used to extract a string containing a specific number of characters from a particular position of a given string.
The SUBSTR() function extracts a substring from the reversed email address, starting from the 4th character. The REVERSE() function is used again to reverse the extracted email ID back to its original order. The extracted email ID is labeled as Email_ID using the AS keyword. ...
[for int]) 在string中从特定位置开始截取特定长度 text substring('michael',from 3 for 2) ch lower(string) 将字符串转化为小写 text lower('MICHAEL') michael upper(string) 将字符串转化为大写 text lower('michael') MICHAEL 1、substring()函数string='abcd/*123456*/efgh' substring(string,'/\*(...
As the most powerful open source database ,Postgresql( hereinafter referred to as pg) Character processing is also the most powerful , First of all, he also has substr,trim And other databases have common functions , Here we introduce a more powerful function substring, Can be like python,jav...
画个图理解这种情况(比如SUBSTRING('abcde',0,2)返回a): 坐标:0 1 2 3 4 5 内容:空 a b c d e 截取:从此截取 截取到这里结束 4.ROUND(); ROUND ( numeric_e-xpression , length [ , function ] ) 这个比较简单,举个例子相信大家就能明白: ...
substring函数:用于提取字符串的子串。应用场景包括从文本中提取关键信息、处理日志等。substring函数介绍 date_trunc函数:用于截断日期或时间的部分。应用场景包括按月、按周等方式统计数据。date_trunc函数介绍 jsonb_agg函数:用于将行转换为JSON数组。应用场景包括将查询结果转换为JSON格式、处理复杂的JSON数据等。jsonb...
SELECT myfunction(3), CatID, CatName FROM myCats 内置函数PostgreSQL 包含许多可在查询中使用的内置函数。 这些内容涉及比较、聚合数据、数学函数等。有关 PostgreSQL 函数的完整列表,请参阅联机文档。内置字符串函数的示例是 substring。SQL 复制 substring (*string* text [ FROM *s...