Text Functions

Text Functions and Operators

This section describes functions and operators for examining and manipulating STRING values.

Name	Description
`string ^@ search_string`	Return true if `string` begins with `search_string`.
`string \|\| string`	Concatenate two strings. Any NULL input results in NULL. See also `concat(string, ...)`.
`string[index]`	Extract a single character using a (1-based) index.
`string[begin:end]`	Extract a string using slice conventions, see slicing.
`string LIKE target`	Returns true if the `string` matches the like specifier (see Pattern Matching).
`string SIMILAR TO regex`	Returns `true` if the `string` matches the `regex`; identical to `regexp_full_match` (see Pattern Matching).
`array_extract(list, index)`	Extract a single character using a (1-based) index.
`array_slice(list, begin, end)`	Extract a string using slice conventions. Negative values are accepted.
`ascii(string)`	Returns an integer that represents the Unicode code point of the first character of the `string`.
`bar(x, min, max[, width])`	Draw a band whose width is proportional to (`x - min`) and equal to `width` characters when `x` = `max`. `width` defaults to 80.
`bit_length(string)`	Number of bits in a string.
`chr(x)`	Returns a character which is corresponding the ASCII code value or Unicode code point.
`concat_ws(separator, string, ...)`	Concatenate many strings, separated by `separator`. NULL inputs are skipped.
`concat(string, ...)`	Concatenate many strings. NULL inputs are skipped. See also `string \|\| string`.
`contains(string, search_string)`	Return true if `search_string` is found within `string`.
`ends_with(string, search_string)`	Return true if `string` ends with `search_string`.
`format_bytes(bytes)`	Converts bytes to a human-readable representation using units based on powers of 2 (KiB, MiB, GiB, etc.).
`format(format, parameters, ...)`	Formats a string using the fmt syntax.
`from_base64(string)`	Convert a base64 encoded string to a character string.
`greatest(x1, x2, ...)`	Selects the largest value using lexicographical ordering. Note that lowercase characters are considered “larger” than uppercase characters and collations are not supported.
`hash(value)`	Returns a `UBIGINT` with the hash of the `value`.
`ilike_escape(string, like_specifier, escape_character)`	Returns true if the `string` matches the `like_specifier` (see Pattern Matching) using case-insensitive matching. `escape_character` is used to search for wildcard characters in the `string`.
`instr(string, search_string)`	Return location of first occurrence of `search_string` in `string`, counting from 1. Returns 0 if no match found.
`least(x1, x2, ...)`	Selects the smallest value using lexicographical ordering. Note that uppercase characters are considered “smaller” than lowercase characters, and collations are not supported.
`left_grapheme(string, count)`	Extract the left-most grapheme clusters.
`left(string, count)`	Extract the left-most count characters.
`length_grapheme(string)`	Number of grapheme clusters in `string`.
`length(string)`	Number of characters in `string`.
`like_escape(string, like_specifier, escape_character)`	Returns true if the `string` matches the `like_specifier` (see Pattern Matching) using case-sensitive matching. `escape_character` is used to search for wildcard characters in the `string`.
`lower(string)`	Convert `string` to lower case.
`lpad(string, count, character)`	Pads the `string` with the character from the left until it has count characters.
`ltrim(string, characters)`	Removes any occurrences of any of the `characters` from the left side of the `string`.
`ltrim(string)`	Removes any spaces from the left side of the `string`.
`md5(string)`	Returns the MD5 hash of the `string` as a `VARCHAR`.
`md5_number(string)`	Returns the MD5 hash of the `string` as a `HUGEINT`.
`md5_number_lower(string)`	Returns the lower 64-bit segment of the MD5 hash of the `string` as a `BIGINT`.
`md5_number_higher(string)`	Returns the higher 64-bit segment of the MD5 hash of the `string` as a `BIGINT`.
`nfc_normalize(string)`	Convert string to Unicode NFC normalized string. Useful for comparisons and ordering if text data is mixed between NFC normalized and not.
`not_ilike_escape(string, like_specifier, escape_character)`	Returns false if the `string` matches the `like_specifier` (see Pattern Matching) using case-sensitive matching. `escape_character` is used to search for wildcard characters in the `string`.
`not_like_escape(string, like_specifier, escape_character)`	Returns false if the `string` matches the `like_specifier` (see Pattern Matching) using case-insensitive matching. `escape_character` is used to search for wildcard characters in the `string`.
`ord(string)`	Return ASCII character code of the leftmost character in a string.
`parse_dirname(path, separator)`	Returns the top-level directory name from the given path. `separator` options: `system`, `both_slash` (default), `forward_slash`, `backslash`.
`parse_dirpath(path, separator)`	Returns the head of the path (the pathname until the last slash) similarly to Python's `os.path.dirname` function. `separator` options: `system`, `both_slash` (default), `forward_slash`, `backslash`.
`parse_filename(path, trim_extension, separator)`	Returns the last component of the path similarly to Python's `os.path.basename` function. If `trim_extension` is true, the file extension will be removed (defaults to `false`). `separator` options: `system`, `both_slash` (default), `forward_slash`, `backslash`.
`parse_path(path, separator)`	Returns a list of the components (directories and filename) in the path similarly to Python's `pathlib.parts` function. `separator` options: `system`, `both_slash` (default), `forward_slash`, `backslash`.
`position(search_string IN string)`	Return location of first occurrence of `search_string` in `string`, counting from 1. Returns 0 if no match found.
`printf(format, parameters...)`	Formats a `string` using printf syntax.
`read_text(source)`	Returns the content from `source` (a filename, a list of filenames, or a glob pattern) as a `VARCHAR`. The file content is first validated to be valid UTF-8. If `read_text` attempts to read a file with invalid UTF-8 an error is thrown suggesting to use `read_blob` instead. See the `read_text` guide for more details.
`regexp_escape(string)`	Escapes special patterns to turn `string` into a regular expression similarly to Python's `re.escape` function.
`regexp_extract(string, pattern[, group = 0])`	If `string` contains the regexp `pattern`, returns the capturing group specified by optional parameter `group` (see Pattern Matching).
`regexp_extract(string, pattern, name_list)`	If `string` contains the regexp `pattern`, returns the capturing groups as a struct with corresponding names from `name_list` (see Pattern Matching).
`regexp_extract_all(string, regex[, group = 0])`	Split the `string` along the `regex` and extract all occurrences of `group`.
`regexp_full_match(string, regex)`	Returns `true` if the entire `string` matches the `regex` (see Pattern Matching).
`regexp_matches(string, pattern)`	Returns `true` if `string` contains the regexp `pattern`, `false` otherwise (see Pattern Matching).
`regexp_replace(string, pattern, replacement)`	If `string` contains the regexp `pattern`, replaces the matching part with `replacement` (see Pattern Matching).
`regexp_split_to_array(string, regex)`	Splits the `string` along the `regex`.
`regexp_split_to_table(string, regex)`	Splits the `string` along the `regex` and returns a row for each part.
`repeat(string, count)`	Repeats the `string` `count` number of times.
`replace(string, source, target)`	Replaces any occurrences of the `source` with `target` in `string`.
`reverse(string)`	Reverses the `string`.
`right_grapheme(string, count)`	Extract the right-most `count` grapheme clusters.
`right(string, count)`	Extract the right-most `count` characters.
`rpad(string, count, character)`	Pads the `string` with the character from the right until it has `count` characters.
`rtrim(string, characters)`	Removes any occurrences of any of the `characters` from the right side of the `string`.
`rtrim(string)`	Removes any spaces from the right side of the `string`.
`sha256(value)`	Returns a `VARCHAR` with the SHA-256 hash of the `value`.
`split_part(string, separator, index)`	Split the `string` along the `separator` and return the data at the (1-based) `index` of the list. If the `index` is outside the bounds of the list, return an empty string (to match PostgreSQL's behavior).
`starts_with(string, search_string)`	Return true if `string` begins with `search_string`.
`str_split_regex(string, regex)`	Splits the `string` along the `regex`.
`string_split_regex(string, regex)`	Splits the `string` along the `regex`.
`string_split(string, separator)`	Splits the `string` along the `separator`.
`strip_accents(string)`	Strips accents from `string`.
`strlen(string)`	Number of bytes in `string`.
`strpos(string, search_string)`	Return location of first occurrence of `search_string` in `string`, counting from 1. Returns 0 if no match found.
`substring(string, start, length)`	Extract substring of `length` characters starting from character `start`. Note that a `start` value of `1` refers to the `first` character of the string.
`substring_grapheme(string, start, length)`	Extract substring of `length` grapheme clusters starting from character `start`. Note that a `start` value of `1` refers to the `first` character of the string.
`to_base64(blob)`	Convert a blob to a base64 encoded string.
`trim(string, characters)`	Removes any occurrences of any of the `characters` from either side of the `string`.
`trim(string)`	Removes any spaces from either side of the `string`.
`unicode(string)`	Returns the Unicode code of the first character of the `string`.
`upper(string)`	Convert `string` to upper case.

`string ^@ search_string`

Description	Return true if `string` begins with `search_string`.
Example	`'abc' ^@ 'a'`
Result	`true`
Alias	`starts_with`

`string || string`

Description	Concatenate two strings. Any `NULL` input results in `NULL`. See also `concat(string, ...)`.
Example	`'Duck' \|\| 'DB'`
Result	`DuckDB`

`string[index]`

Description	Extract a single character using a (1-based) index.
Example	`'DuckDB'[4]`
Result	`k`
Alias	`array_extract`

`string[begin:end]`

Description	Extract a string using slice conventions similar to Python. Missing `begin` or `end` arguments are interpreted as the beginning or end of the list respectively. Negative values are accepted.
Example	`'DuckDB'[:4]`
Result	`Duck`
Alias	`array_slice`

More examples:

SELECT
    'abcdefghi' AS str,
    str[3],    -- get char at position 3, 'c'
    str[3:5],  -- substring from position 3 up to and including position 5, 'cde'
    str[6:],   -- substring from position 6 till the end, 'fghi'
    str[:3],   -- substring from the start up to and including position 3, 'abc'
    str[3:-4], -- substring from positio 3 up to and including the 4th position from the end, 'cdef'
;

`string LIKE target`

Description	Returns true if the `string` matches the like specifier (see Pattern Matching).
Example	`'hello' LIKE '%lo'`
Result	`true`

`string SIMILAR TO regex`

Description	Returns `true` if the `string` matches the `regex`; identical to `regexp_full_match` (see Pattern Matching)
Example	`'hello' SIMILAR TO 'l+'`
Result	`false`

`array_extract(list, index)`

Description	Extract a single character using a (1-based) index.
Example	`array_extract('DuckDB', 2)`
Result	`u`
Aliases	`list_element`, `list_extract`

`array_slice(list, begin, end)`

Description	Extract a string using slice conventions (like in Python). Negative values are accepted.
Example 1	`array_slice('DuckDB', 3, 4)`
Result	`ck`
Example 2	`array_slice('DuckDB', 3, NULL)`
Result	`NULL`
Example 3	`array_slice('DuckDB', 0, -3)`
Result	`Duck`

`ascii(string)`

Description	Returns an integer that represents the Unicode code point of the first character of the `string`.
Example	`ascii('Ω')`
Result	`937`

`bar(x, min, max[, width])`

Description	Draw a band whose width is proportional to (`x - min`) and equal to `width` characters when `x` = `max`. `width` defaults to 80.
Example	`bar(5, 0, 20, 10)`
Result	`██▌`

`bit_length(string)`

Description	Number of bits in a string.
Example	`bit_length('abc')`
Result	`24`

`chr(x)`

Description	Returns a character which is corresponding the ASCII code value or Unicode code point.
Example	`chr(65)`
Result	A

`concat_ws(separator, string, ...)`

Description	Concatenate many strings, separated by `separator`. `NULL` inputs are skipped.
Example	`concat_ws(', ', 'Banana', 'Apple', NULL, 'Melon')`
Result	`Banana, Apple, Melon`

`concat(string, ...)`

Description	Concatenate many strings. `NULL` inputs are skipped. See also `string \|\| string`.
Example	`concat('Hello', ' ', NULL, 'World')`
Result	`Hello World`

`contains(string, search_string)`

Description	Return true if `search_string` is found within `string`.
Example	`contains('abc', 'a')`
Result	`true`

`ends_with(string, search_string)`

Description	Return true if `string` ends with `search_string`.
Example	`ends_with('abc', 'c')`
Result	`true`
Alias	`suffix`

`format_bytes(bytes)`

Description	Converts bytes to a human-readable representation using units based on powers of 2 (KiB, MiB, GiB, etc.).
Example	`format_bytes(16384)`
Result	`16.0 KiB`

`format(format, parameters, ...)`

Description	Formats a string using the fmt syntax.
Example	`format('Benchmark "{}" took {} seconds', 'CSV', 42)`
Result	`Benchmark "CSV" took 42 seconds`

`from_base64(string)`

Description	Convert a base64 encoded string to a character string.
Example	`from_base64('QQ==')`
Result	`'A'`

`greatest(x1, x2, ...)`

Description	Selects the largest value using lexicographical ordering. Note that lowercase characters are considered “larger” than uppercase characters and collations are not supported.
Example	`greatest('abc', 'bcd', 'cde', 'EFG')`
Result	`'cde'`

`hash(value)`

Description	Returns a `UBIGINT` with the hash of the `value`.
Example	`hash('🦆')`
Result	`2595805878642663834`

`ilike_escape(string, like_specifier, escape_character)`

Description	Returns true if the `string` matches the `like_specifier` (see Pattern Matching) using case-insensitive matching. `escape_character` is used to search for wildcard characters in the `string`.
Example	`ilike_escape('A%c', 'a$%C', '$')`
Result	`true`

`instr(string, search_string)`

Description	Return location of first occurrence of `search_string` in `string`, counting from 1. Returns 0 if no match found.
Example	`instr('test test', 'es')`
Result	2

`least(x1, x2, ...)`

Description	Selects the smallest value using lexicographical ordering. Note that uppercase characters are considered “smaller” than lowercase characters, and collations are not supported.
Example	`least('abc', 'BCD', 'cde', 'EFG')`
Result	`'BCD'`

`left_grapheme(string, count)`

Description	Extract the left-most grapheme clusters.
Example	`left_grapheme('🤦🏼‍♂️🤦🏽‍♀️', 1)`
Result	`🤦🏼‍♂️`

`left(string, count)`

Description	Extract the left-most count characters.
Example	`left('Hello🦆', 2)`
Result	`He`

`length_grapheme(string)`

Description	Number of grapheme clusters in `string`.
Example	`length_grapheme('🤦🏼‍♂️🤦🏽‍♀️')`
Result	`2`

`length(string)`

Description	Number of characters in `string`.
Example	`length('Hello🦆')`
Result	`6`

`like_escape(string, like_specifier, escape_character)`

Description	Returns true if the `string` matches the `like_specifier` (see Pattern Matching) using case-sensitive matching. `escape_character` is used to search for wildcard characters in the `string`.
Example	`like_escape('a%c', 'a$%c', '$')`
Result	`true`

`lower(string)`

Description	Convert `string` to lower case.
Example	`lower('Hello')`
Result	`hello`
Alias	`lcase`

`lpad(string, count, character)`

Description	Pads the `string` with the character from the left until it has count characters.
Example	`lpad('hello', 8, '>')`
Result	`>>>hello`

`ltrim(string, characters)`

Description	Removes any occurrences of any of the `characters` from the left side of the `string`.
Example	`ltrim('>>>>test<<', '><')`
Result	`test<<`

`ltrim(string)`

Description	Removes any spaces from the left side of the `string`. In the example, the `␣` symbol denotes a space character.
Example	`ltrim('␣␣␣␣test␣␣')`
Result	`test␣␣`

`md5(string)`

Description	Returns the MD5 hash of the `string` as a `VARCHAR`.
Example	`md5('123')`
Result	`202cb962ac59075b964b07152d234b70`

`md5_number(string)`

Description	Returns the MD5 hash of the `string` as a `HUGEINT`.
Example	`md5_number('123')`
Result	`149263671248412135425768892945843956768`

`md5_number_lower(string)`

Description	Returns the MD5 hash of the `string` as a `BIGINT`.
Example	`md5_number_lower('123')`
Result	`8091599832034528150`

`md5_number_higher(string)`

Description	Returns the MD5 hash of the `string` as a `BIGINT`.
Example	`md5_number_higher('123')`
Result	`6559309979213966368`

`nfc_normalize(string)`

Description	Convert string to Unicode NFC normalized string. Useful for comparisons and ordering if text data is mixed between NFC normalized and not.
Example	`nfc_normalize('ardèch')`
Result	`ardèch`

`not_ilike_escape(string, like_specifier, escape_character)`

Description	Returns false if the `string` matches the `like_specifier` (see Pattern Matching) using case-sensitive matching. `escape_character` is used to search for wildcard characters in the `string`.
Example	`not_ilike_escape('A%c', 'a$%C', '$')`
Result	`false`

`not_like_escape(string, like_specifier, escape_character)`

Description	Returns false if the `string` matches the `like_specifier` (see Pattern Matching) using case-insensitive matching. `escape_character` is used to search for wildcard characters in the `string`.
Example	`not_like_escape('a%c', 'a$%c', '$')`
Result	`false`

`ord(string)`

Description	Return ASCII character code of the leftmost character in a string.
Example	`ord('ü')`
Result	`252`

`parse_dirname(path, separator)`

Description	Returns the top-level directory name from the given path. `separator` options: `system`, `both_slash` (default), `forward_slash`, `backslash`.
Example	`parse_dirname('path/to/file.csv', 'system')`
Result	`path`

`parse_dirpath(path, separator)`

Description	Returns the head of the path (the pathname until the last slash) similarly to Python's `os.path.dirname` function. `separator` options: `system`, `both_slash` (default), `forward_slash`, `backslash`.
Example	`parse_dirpath('/path/to/file.csv', 'forward_slash')`
Result	`/path/to`

`parse_filename(path, trim_extension, separator)`

Description	Returns the last component of the path similarly to Python's `os.path.basename` function. If `trim_extension` is true, the file extension will be removed (defaults to `false`). `separator` options: `system`, `both_slash` (default), `forward_slash`, `backslash`.
Example	`parse_filename('path/to/file.csv', true, 'system')`
Result	`file`

`parse_path(path, separator)`

Description	Returns a list of the components (directories and filename) in the path similarly to Python's `pathlib.parts` function. `separator` options: `system`, `both_slash` (default), `forward_slash`, `backslash`.
Example	`parse_path('/path/to/file.csv', 'system')`
Result	`[/, path, to, file.csv]`

`position(search_string IN string)`

Description	Return location of first occurrence of `search_string` in `string`, counting from 1. Returns 0 if no match found.
Example	`position('b' IN 'abc')`
Result	`2`

`printf(format, parameters...)`

Description	Formats a `string` using printf syntax.
Example	`printf('Benchmark "%s" took %d seconds', 'CSV', 42)`
Result	`Benchmark "CSV" took 42 seconds`

`read_text(source)`

Description	Returns the content from `source` (a filename, a list of filenames, or a glob pattern) as a `VARCHAR`. The file content is first validated to be valid UTF-8. If `read_text` attempts to read a file with invalid UTF-8 an error is thrown suggesting to use `read_blob` instead. See the `read_text` guide for more details.
Example	`read_text('hello.txt')`
Result	`hello\n`

`regexp_escape(string)`

Description	Escapes special patterns to turn `string` into a regular expression similarly to Python's `re.escape` function.
Example	`regexp_escape('http://d.org')`
Result	`http\:\/\/d\.org`

`regexp_extract(string, pattern[, group = 0])`

Description	If `string` contains the regexp `pattern`, returns the capturing group specified by optional parameter `group` (see Pattern Matching).
Example	`regexp_extract('hello_world', '([a-z ]+)_?', 1)`
Result	`hello`

`regexp_extract(string, pattern, name_list)`

Description	If `string` contains the regexp `pattern`, returns the capturing groups as a struct with corresponding names from `name_list` (see Pattern Matching).
Example	`regexp_extract('2023-04-15', '(\d+)-(\d+)-(\d+)', ['y', 'm', 'd'])`
Result	`{'y':'2023', 'm':'04', 'd':'15'}`

`regexp_extract_all(string, regex[, group = 0])`

Description	Split the `string` along the `regex` and extract all occurrences of `group`.
Example	`regexp_extract_all('hello_world', '([a-z ]+)_?', 1)`
Result	`[hello, world]`

`regexp_full_match(string, regex)`

Description	Returns `true` if the entire `string` matches the `regex` (see Pattern Matching).
Example	`regexp_full_match('anabanana', '(an)')`
Result	`false`

`regexp_matches(string, pattern)`

Description	Returns `true` if `string` contains the regexp `pattern`, `false` otherwise (see Pattern Matching).
Example	`regexp_matches('anabanana', '(an)')`
Result	`true`

`regexp_replace(string, pattern, replacement)`

Description	If `string` contains the regexp `pattern`, replaces the matching part with `replacement` (see Pattern Matching).
Example	`regexp_replace('hello', '[lo]', '-')`
Result	`he-lo`

`regexp_split_to_array(string, regex)`

Description	Splits the `string` along the `regex`.
Example	`regexp_split_to_array('hello world; 42', ';? ')`
Result	`['hello', 'world', '42']`
Aliases	`string_split_regex`, `str_split_regex`

`regexp_split_to_table(string, regex)`

Description	Splits the `string` along the `regex` and returns a row for each part.
Example	`regexp_split_to_table('hello world; 42', ';? ')`
Result	Two rows: `'hello'`, `'world'`

`repeat(string, count)`

Description	Repeats the `string` `count` number of times.
Example	`repeat('A', 5)`
Result	`AAAAA`

`replace(string, source, target)`

Description	Replaces any occurrences of the `source` with `target` in `string`.
Example	`replace('hello', 'l', '-')`
Result	`he--o`

`reverse(string)`

Description	Reverses the `string`.
Example	`reverse('hello')`
Result	`olleh`

`right_grapheme(string, count)`

Description	Extract the right-most `count` grapheme clusters.
Example	`right_grapheme('🤦🏼‍♂️🤦🏽‍♀️', 1)`
Result	`🤦🏽‍♀️`

`right(string, count)`

Description	Extract the right-most `count` characters.
Example	`right('Hello🦆', 3)`
Result	`lo🦆`

`rpad(string, count, character)`

Description	Pads the `string` with the character from the right until it has `count` characters.
Example	`rpad('hello', 10, '<')`
Result	`hello<<<<<`

`rtrim(string, characters)`

Description	Removes any occurrences of any of the `characters` from the right side of the `string`.
Example	`rtrim('>>>>test<<', '><')`
Result	`>>>>test`

`rtrim(string)`

Description	Removes any spaces from the right side of the `string`. In the example, the `␣` symbol denotes a space character.
Example	`rtrim('␣␣␣␣test␣␣')`
Result	`␣␣␣␣test`

`sha256(value)`

Description	Returns a `VARCHAR` with the SHA-256 hash of the `value`.
Example	`sha256('🦆')`
Result	`d7a5c5e0d1d94c32218539e7e47d4ba9c3c7b77d61332fb60d633dde89e473fb`

`split_part(string, separator, index)`

Description	Split the `string` along the `separator` and return the data at the (1-based) `index` of the list. If the `index` is outside the bounds of the list, return an empty string (to match PostgreSQL's behavior).
Example	`split_part('a;b;c', ';', 2)`
Result	`b`

`starts_with(string, search_string)`

Description	Return true if `string` begins with `search_string`.
Example	`starts_with('abc', 'a')`
Result	`true`

`str_split_regex(string, regex)`

Description	Splits the `string` along the `regex`.
Example	`str_split_regex('hello world; 42', ';? ')`
Result	`['hello', 'world', '42']`
Aliases	`string_split_regex`, `regexp_split_to_array`

`string_split_regex(string, regex)`

Description	Splits the `string` along the `regex`.
Example	`string_split_regex('hello world; 42', ';? ')`
Result	`['hello', 'world', '42']`
Aliases	`str_split_regex`, `regexp_split_to_array`

`string_split(string, separator)`

Description	Splits the `string` along the `separator`.
Example	`string_split('hello world', ' ')`
Result	`['hello', 'world']`
Aliases	`str_split`, `string_to_array`

`strip_accents(string)`

Description	Strips accents from `string`.
Example	`strip_accents('mühleisen')`
Result	`muhleisen`

`strlen(string)`

Description	Number of bytes in `string`.
Example	`strlen('🦆')`
Result	`4`

`strpos(string, search_string)`

Description	Return location of first occurrence of `search_string` in `string`, counting from 1. Returns 0 if no match found.
Example	`strpos('test test', 'es')`
Result	2
Alias	`instr`

`substring(string, start, length)`

Description	Extract substring of `length` characters starting from character `start`. Note that a `start` value of `1` refers to the `first` character of the string.
Example	`substring('Hello', 2, 2)`
Result	`el`
Alias	`substr`

`substring_grapheme(string, start, length)`

Description	Extract substring of `length` grapheme clusters starting from character `start`. Note that a `start` value of `1` refers to the `first` character of the string.
Example	`substring_grapheme('🦆🤦🏼‍♂️🤦🏽‍♀️🦆', 3, 2)`
Result	`🤦🏽‍♀️🦆`

`to_base64(blob)`

Description	Convert a blob to a base64 encoded string.
Example	`to_base64('A'::blob)`
Result	`QQ==`
Alias	`base64`

`trim(string, characters)`

Description	Removes any occurrences of any of the `characters` from either side of the `string`.
Example	`trim('>>>>test<<', '><')`
Result	`test`

`trim(string)`

Description	Removes any spaces from either side of the `string`.
Example	`trim(' test ')`
Result	`test`

`unicode(string)`

Description	Returns the Unicode code of the first character of the `string`. Returns `-1` when `string` is empty, and `NULL` when `string` is `NULL`.
Example	`[unicode('âbcd'), unicode('â'), unicode(''), unicode(NULL)]`
Result	`[226, 226, -1, NULL]`

`upper(string)`

Description	Convert `string` to upper case.
Example	`upper('Hello')`
Result	`HELLO`
Alias	`ucase`

Text Similarity Functions

These functions are used to measure the similarity of two strings using various similarity measures.

Name	Description
`damerau_levenshtein(s1, s2)`	Extension of Levenshtein distance to also include transposition of adjacent characters as an allowed edit operation. In other words, the minimum number of edit operations (insertions, deletions, substitutions or transpositions) required to change one string to another. Characters of different cases (e.g., `a` and `A`) are considered different.
`editdist3(s1, s2)`	Alias of `levenshtein` for SQLite compatibility. The minimum number of single-character edits (insertions, deletions or substitutions) required to change one string to the other. Characters of different cases (e.g., `a` and `A`) are considered different.
`hamming(s1, s2)`	The Hamming distance between to strings, i.e., the number of positions with different characters for two strings of equal length. Strings must be of equal length. Characters of different cases (e.g., `a` and `A`) are considered different.
`jaccard(s1, s2)`	The Jaccard similarity between two strings. Characters of different cases (e.g., `a` and `A`) are considered different. Returns a number between 0 and 1.
`jaro_similarity(s1, s2)`	The Jaro similarity between two strings. Characters of different cases (e.g., `a` and `A`) are considered different. Returns a number between 0 and 1.
`jaro_winkler_similarity(s1, s2)`	The Jaro-Winkler similarity between two strings. Characters of different cases (e.g., `a` and `A`) are considered different. Returns a number between 0 and 1.
`levenshtein(s1, s2)`	The minimum number of single-character edits (insertions, deletions or substitutions) required to change one string to the other. Characters of different cases (e.g., `a` and `A`) are considered different.
`mismatches(s1, s2)`	Alias for `hamming(s1, s2)`. The number of positions with different characters for two strings of equal length. Strings must be of equal length. Characters of different cases (e.g., `a` and `A`) are considered different.

`damerau_levenshtein(s1, s2)`

Description	Extension of Levenshtein distance to also include transposition of adjacent characters as an allowed edit operation. In other words, the minimum number of edit operations (insertions, deletions, substitutions or transpositions) required to change one string to another. Characters of different cases (e.g., `a` and `A`) are considered different.
Example	`damerau_levenshtein('duckdb', 'udckbd')`
Result	`2`

`editdist3(s1, s2)`

Description	Alias of `levenshtein` for SQLite compatibility. The minimum number of single-character edits (insertions, deletions or substitutions) required to change one string to the other. Characters of different cases (e.g., `a` and `A`) are considered different.
Example	`editdist3('duck', 'db')`
Result	`3`

`hamming(s1, s2)`

Description	The Hamming distance between to strings, i.e., the number of positions with different characters for two strings of equal length. Strings must be of equal length. Characters of different cases (e.g., `a` and `A`) are considered different.
Example	`hamming('duck', 'luck')`
Result	`1`

`jaccard(s1, s2)`

Description	The Jaccard similarity between two strings. Characters of different cases (e.g., `a` and `A`) are considered different. Returns a number between 0 and 1.
Example	`jaccard('duck', 'luck')`
Result	`0.6`

`jaro_similarity(s1, s2)`

Description	The Jaro similarity between two strings. Characters of different cases (e.g., `a` and `A`) are considered different. Returns a number between 0 and 1.
Example	`jaro_similarity('duck', 'duckdb')`
Result	`0.88`

`jaro_winkler_similarity(s1, s2)`

Description	The Jaro-Winkler similarity between two strings. Characters of different cases (e.g., `a` and `A`) are considered different. Returns a number between 0 and 1.
Example	`jaro_winkler_similarity('duck', 'duckdb')`
Result	`0.93`

`levenshtein(s1, s2)`

Description	The minimum number of single-character edits (insertions, deletions or substitutions) required to change one string to the other. Characters of different cases (e.g., `a` and `A`) are considered different.
Example	`levenshtein('duck', 'db')`
Result	`3`

`mismatches(s1, s2)`

Description	Alias for `hamming(s1, s2)`. The number of positions with different characters for two strings of equal length. Strings must be of equal length. Characters of different cases (e.g., `a` and `A`) are considered different.
Example	`mismatches('duck', 'luck')`
Result	`1`

Formatters

`fmt` Syntax

The format(format, parameters...) function formats strings, loosely following the syntax of the {fmt} open-source formatting library.

Format without additional parameters:

SELECT format('Hello world'); -- Hello world

Format a string using {}:

SELECT format('The answer is {}', 42); -- The answer is 42

Format a string using positional arguments:

SELECT format('I''d rather be {1} than {0}.', 'right', 'happy'); -- I'd rather be happy than right.

Format Specifiers

Specifier	Description	Example
`{:d}`	integer	`123456`
`{:E}`	scientific notation	`3.141593E+00`
`{:f}`	float	`4.560000`
`{:o}`	octal	`361100`
`{:s}`	string	`asd`
`{:x}`	hexadecimal	`1e240`
`{:tX}`	integer, `X` is the thousand separator	`123 456`

Formatting Types

Integers:

SELECT format('{} + {} = {}', 3, 5, 3 + 5); -- 3 + 5 = 8

Booleans:

SELECT format('{} != {}', true, false); -- true != false

Format datetime values:

SELECT format('{}', DATE '1992-01-01'); -- 1992-01-01
SELECT format('{}', TIME '12:01:00'); -- 12:01:00
SELECT format('{}', TIMESTAMP '1992-01-01 12:01:00'); -- 1992-01-01 12:01:00

Format BLOB:

SELECT format('{}', BLOB '\x00hello'); -- \x00hello

Pad integers with 0s:

SELECT format('{:04d}', 33); -- 0033

Create timestamps from integers:

SELECT format('{:02d}:{:02d}:{:02d} {}', 12, 3, 16, 'AM'); -- 12:03:16 AM

Convert to hexadecimal:

SELECT format('{:x}', 123_456_789); -- 75bcd15

Convert to binary:

SELECT format('{:b}', 123_456_789); -- 111010110111100110100010101

Print Numbers with Thousand Separators

Integers:

SELECT format('{:,}',  123_456_789); -- 123,456,789
SELECT format('{:t.}', 123_456_789); -- 123.456.789
SELECT format('{:''}', 123_456_789); -- 123'456'789
SELECT format('{:_}',  123_456_789); -- 123_456_789
SELECT format('{:t }', 123_456_789); -- 123 456 789
SELECT format('{:tX}', 123_456_789); -- 123X456X789

Float, double and decimal:

SELECT format('{:,f}',    123456.789); -- 123,456.78900
SELECT format('{:,.2f}',  123456.789); -- 123,456.79
SELECT format('{:t..2f}', 123456.789); -- 123.456,79

`printf` Syntax

The printf(format, parameters...) function formats strings using the printf syntax.

Format without additional parameters:

SELECT printf('Hello world');

Hello world

Format a string using arguments in a given order:

SELECT printf('The answer to %s is %d', 'life', 42);

The answer to life is 42

Format a string using positional arguments %position$formatter, e.g., the second parameter as a string is encoded as %2$s:

SELECT printf('I''d rather be %2$s than %1$s.', 'right', 'happy');

I'd rather be happy than right.

Format Specifiers

Specifier	Description	Example
`%c`	character code to character	`a`
`%d`	integer	`123456`
`%Xd`	integer with thousand seperarator `X` from `,`, `.`, `''`, `_`	`123_456`
`%E`	scientific notation	`3.141593E+00`
`%f`	float	`4.560000`
`%hd`	integer	`123456`
`%hhd`	integer	`123456`
`%lld`	integer	`123456`
`%o`	octal	`361100`
`%s`	string	`asd`
`%x`	hexadecimal	`1e240`

Formatting Types

Integers:

SELECT printf('%d + %d = %d', 3, 5, 3 + 5); -- 3 + 5 = 8

Booleans:

SELECT printf('%s != %s', true, false); -- true != false

Format datetime values:

SELECT printf('%s', DATE '1992-01-01'); -- 1992-01-01
SELECT printf('%s', TIME '12:01:00'); -- 12:01:00
SELECT printf('%s', TIMESTAMP '1992-01-01 12:01:00'); -- 1992-01-01 12:01:00

Format BLOB:

SELECT printf('%s', BLOB '\x00hello'); -- \x00hello

Pad integers with 0s:

SELECT printf('%04d', 33); -- 0033

Create timestamps from integers:

SELECT printf('%02d:%02d:%02d %s', 12, 3, 16, 'AM'); -- 12:03:16 AM

Convert to hexadecimal:

SELECT printf('%x', 123_456_789); -- 75bcd15

Convert to binary:

SELECT printf('%b', 123_456_789); -- 111010110111100110100010101

Thousand Separators

Integers:

SELECT printf('%,d',  123_456_789); -- 123,456,789
SELECT printf('%.d',  123_456_789); -- 123.456.789
SELECT printf('%''d', 123_456_789); -- 123'456'789
SELECT printf('%_d',  123_456_789); -- 123_456_789

Float, double and decimal:

SELECT printf('%,f',   123456.789); -- 123,456.789000
SELECT printf('%,.2f', 123456.789); -- 123,456.79