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Functions for Replacing in Strings

General strings functions and functions for searching in strings are described separately.

overlay​

Replace part of the string input with another string replace, starting at the 1-based index offset.

Syntax

overlay(s, replace, offset[, length])

Parameters

  • s: A string type String.
  • replace: A string type String.
  • offset: An integer type Int (1-based). If offset is negative, it is counted from the end of the string s.
  • length: Optional. An integer type Int. length specifies the length of the snippet within the input string s to be replaced. If length is not specified, the number of bytes removed from s equals the length of replace; otherwise length bytes are removed.

Returned value

Example

SELECT overlay('My father is from Mexico.', 'mother', 4) AS res;

Result:

┌─res──────────────────────┐
│ My mother is from Mexico.│
└──────────────────────────┘
SELECT overlay('My father is from Mexico.', 'dad', 4, 6) AS res;

Result:

┌─res───────────────────┐
│ My dad is from Mexico.│
└───────────────────────┘

overlayUTF8​

Replace part of the string input with another string replace, starting at the 1-based index offset.

Assumes that the string contains valid UTF-8 encoded text. If this assumption is violated, no exception is thrown and the result is undefined.

Syntax

overlayUTF8(s, replace, offset[, length])

Parameters

  • s: A string type String.
  • replace: A string type String.
  • offset: An integer type Int (1-based). If offset is negative, it is counted from the end of the input string s.
  • length: Optional. An integer type Int. length specifies the length of the snippet within the input string s to be replaced. If length is not specified, the number of characters removed from s equals the length of replace; otherwise length characters are removed.

Returned value

Example

SELECT overlay('Mein Vater ist aus Österreich.', 'der Türkei', 20) AS res;

Result:

┌─res───────────────────────────┐
│ Mein Vater ist aus der Türkei.│
└───────────────────────────────┘

replaceOne​

Replaces the first occurrence of the substring pattern in haystack by the replacement string.

Syntax

replaceOne(haystack, pattern, replacement)

replaceAll​

Replaces all occurrences of the substring pattern in haystack by the replacement string.

Syntax

replaceAll(haystack, pattern, replacement)

Alias: replace.

replaceRegexpOne​

Replaces the first occurrence of the substring matching the regular expression pattern (in re2 syntax) in haystack by the replacement string.

replacement can contain substitutions \0-\9. Substitutions \1-\9 correspond to the 1st to 9th capturing group (submatch), substitution \0 corresponds to the entire match.

To use a verbatim \ character in the pattern or replacement strings, escape it using \. Also keep in mind that string literals require extra escaping.

Syntax

replaceRegexpOne(haystack, pattern, replacement)

Example

Converting ISO dates to American format:

SELECT DISTINCT
    EventDate,
    replaceRegexpOne(toString(EventDate), '(\\d{4})-(\\d{2})-(\\d{2})', '\\2/\\3/\\1') AS res
FROM test.hits
LIMIT 7
FORMAT TabSeparated

Result:

2014-03-17      03/17/2014
2014-03-18      03/18/2014
2014-03-19      03/19/2014
2014-03-20      03/20/2014
2014-03-21      03/21/2014
2014-03-22      03/22/2014
2014-03-23      03/23/2014

Copying a string ten times:

SELECT replaceRegexpOne('Hello, World!', '.*', '\\0\\0\\0\\0\\0\\0\\0\\0\\0\\0') AS res

Result:

┌─res────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│ Hello, World!Hello, World!Hello, World!Hello, World!Hello, World!Hello, World!Hello, World!Hello, World!Hello, World!Hello, World! │
└────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘

replaceRegexpAll​

Like replaceRegexpOne but replaces all occurrences of the pattern.

Alias: REGEXP_REPLACE.

Example

SELECT replaceRegexpAll('Hello, World!', '.', '\\0\\0') AS res

Result:

┌─res────────────────────────┐
│ HHeelllloo,,  WWoorrlldd!! │
└────────────────────────────┘

As an exception, if a regular expression worked on an empty substring, the replacement is not made more than once, e.g.:

SELECT replaceRegexpAll('Hello, World!', '^', 'here: ') AS res

Result:

┌─res─────────────────┐
│ here: Hello, World! │
└─────────────────────┘

regexpQuoteMeta​

Adds a backslash before these characters with special meaning in regular expressions: \0, \\, |, (, ), ^, $, ., [, ], ?, *, +, {, :, -.

This implementation slightly differs from re2::RE2::QuoteMeta. It escapes zero byte as \0 instead of \x00 and it escapes only required characters. For more information, see RE2

Syntax

regexpQuoteMeta(s)

format​

Format the pattern string with the values (strings, integers, etc.) listed in the arguments, similar to formatting in Python. The pattern string can contain replacement fields surrounded by curly braces {}. Anything not contained in braces is considered literal text and copied verbatim into the output. Literal brace character can be escaped by two braces: {{ '{{' }} and {{ '}}' }}. Field names can be numbers (starting from zero) or empty (then they are implicitly given monotonically increasing numbers).

Syntax

format(pattern, s0, s1, ...)

Example

SELECT format('{1} {0} {1}', 'World', 'Hello')
┌─format('{1} {0} {1}', 'World', 'Hello')─┐
│ Hello World Hello                       │
└─────────────────────────────────────────┘

With implicit numbers:

SELECT format('{} {}', 'Hello', 'World')
┌─format('{} {}', 'Hello', 'World')─┐
│ Hello World                       │
└───────────────────────────────────┘

translate​

Replaces characters in the string s using a one-to-one character mapping defined by from and to strings. from and to must be constant ASCII strings. If from and to have equal sizes, each occurrence of the 1st character of first in s is replaced by the 1st character of to, the 2nd character of first in s is replaced by the 2nd character of to, etc. If from contains more characters than to, all occurrences of the characters at the end of from that have no corresponding character in to are deleted from s. Non-ASCII characters in s are not modified by the function.

Syntax

translate(s, from, to)

Example

SELECT translate('Hello, World!', 'delor', 'DELOR') AS res

Result:

┌─res───────────┐
│ HELLO, WORLD! │
└───────────────┘

from and to arguments have different lengths:

SELECT translate('clickhouse', 'clickhouse', 'CLICK') AS res

Result:

┌─res───┐
│ CLICK │
└───────┘

translateUTF8​

Like translate but assumes s, from and to are UTF-8 encoded strings.

Syntax

translateUTF8(s, from, to)

Parameters

Returned value

Examples

Query:

SELECT translateUTF8('Münchener Straße', 'üß', 'us') AS res;
┌─res──────────────┐
│ Munchener Strase │
└──────────────────┘

printf​

The printf function formats the given string with the values (strings, integers, floating-points etc.) listed in the arguments, similar to printf function in C++. The format string can contain format specifiers starting with % character. Anything not contained in % and the following format specifier is considered literal text and copied verbatim into the output. Literal % character can be escaped by %%.

Syntax

printf(format, arg1, arg2, ...)

Example

Query:

select printf('%%%s %s %d', 'Hello', 'World', 2024);
┌─printf('%%%s %s %d', 'Hello', 'World', 2024)─┐
│ %Hello World 2024                            │
└──────────────────────────────────────────────┘