函数：regexp_matches(string text, pattern text [, flags text])

说明：Return all captured substrings resulting from matching a POSIX regular expression against the string. See Section 9.7.3 for more information. 对字符串按正则表达式进行匹配，如果存在则会在结果数组中表示出来

例子：regexp_matches('foobarbequebaz', '(bar)(beque)') = {bar,beque}

函数：regexp_replace(string text, pattern text, replacement text [, flags text])

说明：Replace substring(s) matching a POSIX regular expression. See Section 9.7.3 for more information. 利用正则表达式对字符串进行替换

例子：regexp_replace('Thomas', '.[mN]a.', 'M') = ThM

函数：regexp_split_to_array(string text, pattern text [, flags text ])

说明：Split string using a POSIX regular expression as the delimiter. See Section 9.7.3 for more information. 利用正则表达式将字符串分割成数组

例子：regexp_split_to_array('hello world', E'\\s+') = {hello,world}

函数：regexp_split_to_table(string text, pattern text [, flags text])

说明：Split string using a POSIX regular expression as the delimiter. See Section 9.7.3 for more information. 利用正则表达式将字符串分割成表格

例子：regexp_split_to_table('hello world', E'\\s+') =

hello

world

(2 rows)

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函数：repeat(string text, number int)

说明：Repeat string the specified number of times 重复字符串一指定次数

例子：repeat('Pg', 4) = PgPgPgPg

函数：replace(string text, from text, to text)

说明：Replace all occurrences in string of substring from with substring to 将字符的某一子串替换成另一子串

例子：('abcdefabcdef', 'cd', 'XX') = abXXefabXXef

函数：rpad(string text, length int [, fill text])

说明：Fill up the string to length length by appending the characters fill (a space by default). If the string is already longer than length then it is truncated. 对字符串进行填充，填充内容为指定的字符串

例子：rpad('hi', 5, 'xy') = hixyx

函数：rtrim(string text [, characters text])

说明：Remove the longest string containing only characters from characters (a space by default) from the end of string

去除字符串右边指定的字符

例子：rtrim('trimxxxx', 'x') = trim

函数：split_part(string text, delimiter text, field int)

说明：Split string on delimiter and return the given field (counting from one) 对字符串按指定子串进行分割，并返回指定的数值位置的值

例子：split_part('abc~@~def~@~ghi', '~@~', 2) = def

函数：strpos(string, substring)

说明：Location of specified substring (same as position(substring in string), but note the reversed argument order) 指定字符串在目标字符串的位置

例子：strpos('high', 'ig') = 2

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函数：substr(string, from [, count])

说明：Extract substring (same as substring(string from from for count)) 截取子串

例子：substr('alphabet', 3, 2) = ph

函数：to_ascii(string text [, encoding text])

说明：Convert string to ASCII from another encoding (only supports conversion from LATIN1, LATIN2, LATIN9, and WIN1250 encodings) 将字符串转换成ascii编码字符串

例子：to_ascii('Karel') = Karel

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函数：to_hex(number int or bigint)

说明：Convert number to its equivalent hexadecimal representation 　对数值进行十六进制编码

例子：to_hex(2147483647) = 7fffffff

函数：translate(string text, from text, to text)

说明：Any character in string that matches a character in the from set is replaced by the corresponding character in the to set 将字符串中某些匹配的字符替换成指定字符串，目标字符与源字符都可以同时指定多个

例子：translate('12345', '14', 'ax') = a23x5