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String Functions

Scalar functions for string processing and manipulation that can be used in any expression context.

replace(string, pattern)​

Replaces all occurrences of a pattern in a string.

Parameters​

  • string - String expression to search within
  • pattern - String expression representing the text to replace

Description​

The replace() function removes all occurrences of the specified pattern from the input string. This function performs literal string replacement, not pattern matching. If the pattern is not found, the original string is returned unchanged.

starts_with(string, prefix)​

Tests whether a string starts with a specified prefix.

Parameters​

  • string - String expression to test
  • prefix - String expression representing the prefix to check for

Description​

The starts_with() function returns true if the input string begins with the specified prefix, false otherwise. The comparison is case-sensitive. An empty prefix will always return true for any string.

ends_with(string, suffix)​

Tests whether a string ends with a specified suffix.

Parameters​

  • string - String expression to test
  • suffix - String expression representing the suffix to check for

Description​

The ends_with() function returns true if the input string ends with the specified suffix, false otherwise. The comparison is case-sensitive. An empty suffix will always return true for any string.

contains(string, substring)​

Tests whether a string contains a specified substring.

Parameters​

  • string - String expression to search within
  • substring - String expression representing the text to search for

Description​

The contains() function returns true if the input string contains the specified substring anywhere within it, false otherwise. The comparison is case-sensitive. An empty substring will always return true for any string.

lower(string)​

Converts a string to lowercase.

Parameters​

  • string - String expression to convert

Description​

The lower() function converts all uppercase characters in the input string to their lowercase equivalents. Characters that are already lowercase or non-alphabetic characters remain unchanged.

upper(string)​

Converts a string to uppercase.

Parameters​

  • string - String expression to convert

Description​

The upper() function converts all lowercase characters in the input string to their uppercase equivalents. Characters that are already uppercase or non-alphabetic characters remain unchanged.

url_encode(string)​

Encodes a string for safe use in URL query parameters (application/x-www-form-urlencoded style).

Parameters​

  • string - String expression to encode

Description​

The url_encode() function escapes characters so the value can be used in URL query parameter names and values. Alphanumeric characters and .-*_ are left unchanged; ASCII space is encoded as +; all other bytes are encoded as %XX using uppercase hexadecimal UTF-8 byte values.

url_decode(string)​

Decodes a URL-encoded string (inverse of url_encode).

Parameters​

  • string - String expression to decode

Description​

The url_decode() function reverses url_encode(): + is decoded to space, %XX sequences are decoded to their byte values, and the result is interpreted as UTF-8. Invalid encodings may produce an error depending on the execution engine.

substr(string, start, end)​

Returns a substring from start index to end index (exclusive).

Parameters​

  • string - String expression to extract from
  • start - Integer expression for the starting index (0-based, supports negative indices)
  • end - Integer expression for the ending index (exclusive, supports negative indices)

Description​

The substr() function returns a new string containing characters from the start index up to but not including the end index. Both indices are 0-based and support negative values, where -1 refers to the last character, -2 to the second-last, and so on. If start is greater than or equal to end, an empty string is returned. The function handles out-of-bounds indices gracefully by clamping them to valid string boundaries.

uuid()​

Generates a random UUID v4 string.

Parameters​

This function takes no parameters.

Description​

The uuid() function returns a new random UUID (universally unique identifier) string each time you call it. The generated value follows the UUID v4 format (e.g., "550e8400-e29b-41d4-a716-446655440000"). Each invocation produces a different value.

uuid5(name)​

Generates a deterministic UUID v5 string (RFC 4122).

Parameters​

  • name - String expression to derive the UUID from

Description​

The uuid5() function returns a deterministic UUID (universally unique identifier) string derived from the input name. The generated value follows the UUID v5 format (e.g., xxxxxxxx-xxxx-5xxx-8xxx-xxxxxxxxxxxx). The same input always produces the same output.

len(string)​

Returns the length of a string in characters.

Parameters​

  • string - String expression to measure

Description​

The len() function returns the number of characters in the input string. This counts Unicode characters, not bytes, so multi-byte characters are counted as single characters. An empty string returns 0.