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There also exist algebraic operators (+,  -, *, /) to perform string concatenation and deletion.

SELECT "Hello"+"World" FROM Stream
=> "HelloWorld"
SELECT "HelloWorld"-"World" FROM Stream
=> "Hello"
SELECT "HelloWorld"*3 FROM Stream
=> "HelloWorldHelloWorldHelloWorld"
SELECT "HelloWorldHelloWorldHelloWorld"/"World" FROM Stream
=> 3

Concat(String s1, String s2)

Returns a new string that is a concatenating the arguments.

SubString(String s, Number begin, Number end)

Returns a new string that is a substring of the value with given begin and end index

SELECT substring("Hello World",1,3) FROM Stream
=> "el"

SubString(String s, Number begin)

Returns a new string that is a substring of the value starting at the begin index until the end of the string

SELECT substring("Hello World",1) FROM Stream
=> "ello World"

Length(String s)

Returns the length of a string.

SELECT length("Hello") FROM Stream
=> 5

Upper(String s)

Returns the string converted to uppercase.
 

SELECT upper("Hello World") FROM Stream
=> "HELLO WORLD"

Lower(String s)

Returns the string converted to lowercase.

SELECT lower("Hello World") FROM Stream
=> "hello world"

Parsing of Strings

The most functions provide one return value. Sometimes it is needed to split an incoming attribute to multiple values

split(String s, String delimiter, Number index)

This function returns number (third parameter) strings from the input string (first parameter) with the delimiter (second parameter).

SELECT split(input,",",3) FROM stream

Remark: There is no way to parse different types with this function. Each incoming string must contains exactly the given numbers of inputs.