ekuiper-new/docs/en_US/sqls/functions/string_functions.md

String Functions

String functions are used to manipulate string data.

CONCAT

concat(col1, col2, ...)

Concatenates arrays or strings. This function accepts any number of arguments and returns a string or an array.

ENDSWITH

endswith(col1, col2)

Returns a boolean indicating whether the first string argument ends with the second string argument.

FORMAT_TIME

format_time(col, format)

Format a datetime to string. The 'col' will be cast to datetime type if it is bigint, float or string type before formatting. Please check format patterns for how to compose the format.

Format_time patterns

A pattern is used to create a format string. Patterns are based on a simple sequence of letters and symbols which is common in many languages like Java, etc. The supported symbols in Kuiper are

Symbol	Meaning	Example
G	era	G(AD)
Y	year	YYYY(2004), YY(04)
M	month	M(1), MM(01), MMM(Jan), MMMM(January)
d	day of month	d(2), dd(02)
E	day of week	EEE(Mon), EEEE(Monday)
H	hour in 24 hours format	HH(15)
h	hour in 12 hours format	h(2), hh(03)
a	AM or PM	a(PM)
m	minute	m(4), mm(04)
s	second	s(5), ss(05)
S	fraction of second	S(.0), SS(.00), SSS(.000)
z	time zone name	z(MST)
Z	4 digits time zone offset	Z(-0700)
X	time zone offset	X(-07), XX(-0700), XXX(-07:00)

Examples:

• YYYY-MM-dd T HH:mm:ss -> 2006-01-02 T 15:04:05
• YYYY/MM/dd HH:mm:ssSSS XXX -> 2006/01/02 15:04:05.000 -07:00

INDEXOF

indexof(col1, col2)

Returns the first index (0-based) of the second argument as a substring in the first argument.

LENGTH

length(col)

Returns the number of characters in the provided string.

LOWER

lower(col)

Returns the lowercase version of the given string.

LPAD

lpad(col, 2)

Returns the string argument, padded on the left side with the number of spaces specified by the second argument.

LTRIM

ltrim(col)

Removes all leading whitespace (tabs and spaces) from the provided string.

NUMBYTES

numbytes(col)

Returns the number of bytes in the UTF-8 encoding of the provided string.

REGEXP_MATCHES

regexp_matches(col, regex)

Returns true if the string (first argument) contains a match for the regular expression.

REGEXP_REPLACE

regexp_replace(col, regex, replacement)

Replaces all substrings of the specified string value that matches regexp with replacement.

REGEXP_SUBSTRING

regexp_substring(col, regex)

Returns the first substring of the specified string value that matches regexp.

RPAD

rpad(col, 2)

Returns the string argument, padded on the right side with the number of spaces specified by the second argument.

RTRIM

rtrim(col)

Removes all trailing whitespace (tabs and spaces) from the provided string.

SUBSTRING

substring(col, start, length)

Returns the substring of the specified string value starting at the specified index position (0-based, inclusive) for up to the specified length of characters.

STARTSWITH

startswith(col, str)

Returns a boolean indicating whether the first string argument starts with the second string argument.

SPLIT_VALUE

split_value(col, str_splitter, index)

Split the value of the 1st parameter with the 2nd parameter, and return the value of split array that indexed with the 3rd parameter.

For example, split_value("/test/device001/message","/",0) AS a, the returned value of function is empty;

split_value("/test/device001/message","/",3) AS a, the returned value of function is message.

TRIM

trim(col)

Removes all leading and trailing whitespace (tabs and spaces) from the provided string.

UPPER

upper(col)

Returns the uppercase version of the given string.