This section describes functions and operators for examining and manipulating string values. ␣ denotes a space character.
| Function | Description | Example | Result |
|---|---|---|---|
string ^@ search_string |
Alias for starts_with. |
'abc' ^@ 'a' |
true |
string || string |
String concatenation | 'Duck' || 'DB' |
DuckDB |
string[index] |
Alias for array_extract. |
'DuckDB'[4] |
'k' |
string[begin:end] |
Alias for array_slice. Missing arguments are interpreted as NULLs. |
'DuckDB'[:4] |
'Duck' |
array_extract(list, index) |
Extract a single character using a (1-based) index. | array_extract('DuckDB', 2) |
'u' |
array_slice(list, begin, end) |
Extract a string using slice conventions. NULLs are interpreted as the bounds of the string. Negative values are accepted. |
array_slice('DuckDB', 5, NULL) |
'DB' |
ascii(string) |
Returns an integer that represents the Unicode code point of the first character of the string | ascii('Ω') |
937 |
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. | bar(5, 0, 20, 10) |
██▌ |
base64(blob) |
Convert a blob to a base64 encoded string. Alias of to_base64. | base64('A'::blob) |
'QQ==' |
bit_length(string) |
Number of bits in a string. | bit_length('abc') |
24 |
chr(x) |
returns a character which is corresponding the ASCII code value or Unicode code point | chr(65) |
A |
concat(string, ...) |
Concatenate many strings together | concat('Hello', ' ', 'World') |
Hello World |
concat_ws(separator, string, ...) |
Concatenate strings together separated by the specified separator | concat_ws(',', 'Banana', 'Apple', 'Melon') |
Banana,Apple,Melon |
contains(string, search_string) |
Return true if search_string is found within string | contains('abc','a') |
true |
format(format, parameters...) |
Formats a string using fmt syntax | format('Benchmark "{}" took {} seconds', 'CSV', 42) |
Benchmark "CSV" took 42 seconds |
from_base64(string) |
Convert a base64 encoded string to a character string. | from_base64('QQ==') |
'A' |
hash(value) |
Returns an integer with the hash of the value | hash('🦆') |
2595805878642663834 |
instr(string, search_string) |
Return location of first occurrence of search_string in string, counting from 1. Returns 0 if no match found. |
instr('test test','es') |
2 |
lcase(string) |
Alias of lower. Convert string to lower case |
lcase('Hello') |
hello |
left(string, count) |
Extract the left-most count characters | left('Hello🦆', 2) |
He |
left_grapheme(string, count) |
Extract the left-most grapheme clusters | left_grapheme('🤦🏼♂️🤦🏽♀️', 1) |
🤦🏼♂️ |
length(string) |
Number of characters in string | length('Hello🦆') |
6 |
length_grapheme(string) |
Number of grapheme clusters in string | length_grapheme('🤦🏼♂️🤦🏽♀️') |
2 |
string LIKE target |
Returns true if the string matches the like specifier (see Pattern Matching) | 'hello' LIKE '%lo' |
true |
like_escape(string, like_specifier, escape_character) |
Returns true if the string matches the like_specifier (see Pattern Matching). escape_character is used to search for wildcard characters in the string. | like_escape('a%c', 'a$%c', '$') |
true |
list_element(string, index) |
An alias for array_extract. |
list_element('DuckDB', 2) |
'u' |
list_extract(string, index) |
An alias for array_extract. |
list_extract('DuckDB', 2) |
'u' |
lower(string) |
Convert string to lower case | lower('Hello') |
hello |
lpad(string, count, character) |
Pads the string with the character from the left until it has count characters | lpad('hello', 10, '>') |
>>>>>hello |
ltrim(string) |
Removes any spaces from the left side of the string | ltrim('␣␣␣␣test␣␣') |
test␣␣ |
ltrim(string, characters) |
Removes any occurrences of any of the characters from the left side of the string | ltrim('>>>>test<<', '><') |
test<< |
md5(value) |
Returns the MD5 hash of the value | md5('123') |
'202cb962ac59075b964b07152d234b70' |
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. | nfc_normalize('ardèch') |
arde`ch |
not_like_escape(string, like_specifier, escape_character) |
Returns false if the string matches the like_specifier (see Pattern Matching). escape_character is used to search for wildcard characters in the string. | like_escape('a%c', 'a$%c', '$') |
true |
ord(string) |
Return ASCII character code of the leftmost character in a string. | ord('ü') |
252 |
position(search_string in string) |
Return location of first occurrence of search_string in string, counting from 1. Returns 0 if no match found. |
position('b' in 'abc') |
2 |
prefix(string, search_string) |
Return true if string starts with search_string. | prefix('abc', 'ab') |
true |
printf(format, parameters...) |
Formats a string using printf syntax | printf('Benchmark "%s" took %d seconds', 'CSV', 42) |
Benchmark "CSV" took 42 seconds |
regexp_full_match(string, regex) |
Returns true if the entire string matches the regex (see Pattern Matching) | regexp_full_match('anabanana', '(an)*') |
false |
regexp_matches(string, regex) |
Returns true if a part of string matches the regex (see Pattern Matching) | regexp_matches('anabanana', '(an)*') |
true |
regexp_replace(string, regex, replacement, modifiers) |
Replaces the first occurrence of regex with the replacement, use 'g' modifier to replace all occurrences instead (see Pattern Matching) |
select regexp_replace('hello', '[lo]', '-') |
he-lo |
regexp_split_to_array(string, regex) |
Alias of string_split_regex. Splits the string along the regex |
regexp_split_to_array('hello␣world; 42', ';?␣') |
['hello', 'world', '42'] |
regexp_extract(string, regex[, group = 0]) |
Split the string along the regex and extract first occurrence of group | regexp_extract('hello_world', '([a-z ]+)_?', 1) |
hello |
regexp_extract_all(string, regex[, group = 0]) |
Split the string along the regex and extract all occurrences of group | regexp_extract_all('hello_world', '([a-z ]+)_?', 1) |
[hello, world] |
repeat(string, count) |
Repeats the string count number of times | repeat('A', 5) |
AAAAA |
replace(string, source, target) |
Replaces any occurrences of the source with target in string | replace('hello', 'l', '-') |
he--o |
reverse(string) |
Reverses the string | reverse('hello') |
olleh |
right(string, count) |
Extract the right-most count characters | right('Hello🦆', 3) |
lo🦆 |
right_grapheme(string, count) |
Extract the right-most count grapheme clusters | right_grapheme('🤦🏼♂️🤦🏽♀️', 1) |
🤦🏽♀️ |
rpad(string, count, character) |
Pads the string with the character from the right until it has count characters | rpad('hello', 10, '<') |
hello<<<<< |
rtrim(string) |
Removes any spaces from the right side of the string | rtrim('␣␣␣␣test␣␣') |
␣␣␣␣test |
rtrim(string, characters) |
Removes any occurrences of any of the characters from the right side of the string | rtrim('>>>>test<<', '><') |
>>>>test |
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 Postgres behavior). | split_part('a|b|c', '|', 2) |
b |
starts_with(string, search_string) |
Return true if string begins with search_string | starts_with('abc','a') |
true |
string SIMILAR TO regex |
Returns true if the string matches the regex; identical to regexp_full_match (see Pattern Matching) |
'hello' SIMILAR TO 'l+' |
false |
strlen(string) |
Number of bytes in string | strlen('🦆') |
4 |
strpos(string, search_string) |
Alias of instr. Return location of first occurrence of search_string in string, counting from 1. Returns 0 if no match found. |
strpos('test test','es') |
2 |
strip_accents(string) |
Strips accents from string | strip_accents('mühleisen') |
muhleisen |
str_split(string, separator) |
Alias of string_split. Splits the string along the separator |
str_split('hello␣world', '␣') |
['hello', 'world'] |
str_split_regex(string, regex) |
Alias of string_split_regex. Splits the string along the regex |
str_split_regex('hello␣world; 42', ';?␣') |
['hello', 'world', '42'] |
string_split(string, separator) |
Splits the string along the separator | string_split('hello␣world', '␣') |
['hello', 'world'] |
string_split_regex(string, regex) |
Splits the string along the regex | string_split_regex('hello␣world; 42', ';?␣') |
['hello', 'world', '42'] |
string_to_array(string, separator) |
Alias of string_split. Splits the string along the separator |
string_to_array('hello␣world', '␣') |
['hello', 'world'] |
substr(string, start, length) |
Alias of substring. Extract substring of length characters starting from character start. Note that a start value of 1 refers to the first character of the string. |
substr('Hello', 2, 2) |
el |
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('Hello', 2, 2) |
el |
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. |
substring_grapheme('🦆🤦🏼♂️🤦🏽♀️🦆', 3, 2) |
🤦🏽♀️🦆 |
suffix(string, search_string) |
Return true if string ends with search_string. | suffix('abc', 'bc') |
true |
strpos(string, characters) |
Alias of instr. Return location of first occurrence of characters in string, counting from 1. Returns 0 if no match found. |
strpos('test test','es') |
2 |
to_base64(blob) |
Convert a blob to a base64 encoded string. Alias of base64. | to_base64('A'::blob) |
QQ== |
trim(string) |
Removes any spaces from either side of the string | trim('␣␣␣␣test␣␣') |
test |
trim(string, characters) |
Removes any occurrences of any of the characters from either side of the string | trim('>>>>test<<', '><') |
test |
ucase(string) |
Alias of upper. Convert string to upper case |
ucase('Hello') |
HELLO |
unicode(string) |
Returns the unicode code of the first character of the string | unicode('ü') |
252 |
upper(string) |
Convert string to upper case | upper('Hello') |
HELLO |
Text Similarity Functions
These functions are used to measure the similarity of two strings using various metrics.
| Function | Description | Example | Result |
|---|---|---|---|
editdist3(string, string) |
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. Different case is considered different. |
editdist3('duck','db') |
3 |
hamming(string, string) |
The number of positions with different characters for 2 strings of equal length. Different case is considered different. | hamming('duck','luck') |
1 |
jaccard(string, string) |
The Jaccard similarity between two strings. Different case is considered different. Returns a number between 0 and 1. | jaccard('duck','luck') |
0.6 |
jaro_similarity(string, string) |
The Jaro similarity between two strings. Different case is considered different. Returns a number between 0 and 1. | jaro_similarity('duck','duckdb') |
0.88 |
jaro_winkler_similarity(string, string) |
The Jaro-Winkler similarity between two strings. Different case is considered different. Returns a number between 0 and 1. | jaro_winkler_similarity('duck','duckdb') |
0.93 |
levenshtein(string, string) |
The minimum number of single-character edits (insertions, deletions or substitutions) required to change one string to the other. Different case is considered different. | levenshtein('duck','db') |
3 |
damerau_levenshtein(string, string) |
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. Different case is considered different. | damerau_levenshtein('duckdb', 'udckbd') |
2 |
mismatches(string, string) |
The number of positions with different characters for 2 strings of equal length. Different case is considered different. | mismatches('duck','luck') |
1 |