PostgreSQL offers many data types. Strings are the most significant and most commonly used data types. Sometimes we need to search for some terms/substrings in the strings. PostgreSQL provides many approaches to find if a string contains a substring. This article comprises methods with which we ...
其语法为:Instr(string, substring, position, occurrence)。 string:代表源字符串(写入字段则表示此字段的内容)。 substring:代表想从源字符串中查找的子串。 position:代表查找的开始位置,该参数可选的,默认为1。 occurrence:代表想从源字符中查找出第几次出现的substring,该参数也是可选的,默认为1。 position 的...
说明:Returnthe given string suitably quotedtobe usedasan identifierinan SQL statement string. Quotes are addedonlyifnecessary (i.e.,ifthe stringcontainsnon-identifier charactersorwould becase-folded). Embedded quotes are properly doubled. 对某一字符串加上两引号 例子:quote_ident('Foo bar')="Foo ...
insert(int offset, String str) char charAt(int index) delete(int start, int end) deleteCharAt(int index) replace(int start, int end, String str) String substring(int start) int indexOf(String str) int lastIndexOf(String str) reverse() 没有equals(),toUpperCase(),startWith(),contains(),...
SUBSTRING(string, pattern); Or you can use the following syntax: SUBSTRING(string FROM pattern) If the SUBSTRING() function finds no match, it returns NULL. If the pattern contains any parentheses, the SUBSTRING() function returns the text that matches the first parenthesized subexpression. The ...
PostgreSQL provides a built-in function namedSUBSTRING()that extracts a substring from any specific string. TheSUBSTRING()function accepts three parameters: a string, starting position, and length. The starting position” and “length” parameters are optional that can be skipped depending on ...
在PostgreSQL中遍历string[]可以使用FOREACH语句或者使用unnest函数结合SELECT语句来实现。 使用FOREACH语句遍历string[]: FOREACH语句是一种循环语句,可以用于遍历数组中的每个元素。以下是使用FOREACH语句遍历string[]的示例: 代码语言:sql 复制 DO $$ DECLARE 代码语言:txt 复制 arr_string text[] := ARRAY['apple...
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.
函数：string||string 说明：Stringconcatenation字符串连接操作 例子：'Post'||'greSQL' ＝ PostgreSQL 函数：string||non-stringornon-string||string 说明：Stringconcatenationwithonenon-stringinput字符串与非字符串类型进行连接操作 例子：'Value:'||42=Value:42 函数：bit_length(string) 说明：Number...
函数:overlay(string placing string from int [for int]) 说明:Replace substring 替换字符串中任意长度的子字串为新字符串 例子:select overlay('I am pmars' placing 'ming' from 6 for 5); = "I am ming" 函数:position(substring in string) ...