substr (Function)

Returns a substring of the input string by considering a subset or all of the following factors: starting index, length, regular expression, and regex group number.

Syntax

<STRING> str:substr(<STRING> input.string, <INT> begin.index)
<STRING> str:substr(<STRING> input.string, <INT> begin.index, <INT> length)
<STRING> str:substr(<STRING> input.string, <STRING> regex)
<STRING> str:substr(<STRING> input.string, <STRING> regex, <INT> group.number)

Query Parameters

Name	Description	Default Value	Possible Data Types	Optional	Dynamic
input.string	The input string to be processed.		STRING	No	Yes
begin.index	Starting index to consider for the substring.	-	INT	Yes	Yes
length	The length of the substring.	input.string.length - begin.index	INT	Yes	Yes
regex	The regular expression that should be matched with the input string.	-	STRING	Yes	Yes
group.number	The regex group number.	0	INT	Yes	Yes

Example 1

@info(name = 'substringExample')
SELECT str:substr('Hello World', 0, 5) AS substringResult;

The substringExample demonstrates the use of the str:substr() function to extract a substring from a given input string. In this example, the input string is 'Hello World', and the substring is extracted from index 0 to index 4 (the length of the substring is 5). The function returns 'Hello' as the output.

Example 2

@info(name = 'substringExample2')
SELECT str:substr('Hello World', 6, 5) AS substringResult;

The substringExample2 uses the str:substr() function to extract a substring from a given input string. In this example, the input string is 'Hello World', and the substring is extracted from index 6 to index 10 (the length of the substring is 5). The function returns 'World' as the output.

Example 3

@info(name = 'substringExample3')
SELECT str:substr('Hello World', 0, 11) AS substringResult;

The substringExample3 uses the str:substr() function to extract a substring from a given input string. In this example, the input string is 'Hello World', and the substring is extracted from index 0 to index 10 (the length of the substring is 11). The function returns 'Hello World' as the output.

Example 4

@info(name = 'substringExample4')
SELECT str:substr('Hello World', 3, 4) AS substringResult;

The substringExample4 uses the str:substr() function to extract a substring from a given input string. In this example, the input string is 'Hello World', and the substring is extracted from index 3 to index 6 (the length of the substring is 4). The function returns 'lo W' as the output.

Example 5

CREATE STREAM InputDataStream (eventTime long, inputString string, startIndex int, length int);
CREATE SINK STREAM OutputStream (eventTime long, substringResult string);

@info(name = 'substringStreamWorker')
INSERT INTO OutputStream
SELECT eventTime, str:substr(inputString, startIndex, length) AS substringResult
FROM InputDataStream;

The substringStreamWorker processes events from the InputDataStream and uses the str:substr() function to extract a substring from the inputString attribute, starting at the specified startIndex and having the specified length. The query outputs the eventTime and the resulting substringResult for each event to the OutputStream.