> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-mintlify-3a82795f.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

> Documentation for string replacement functions

# Functions for string replacement

[General strings functions](/reference/functions/regular-functions/string-functions) and [functions for searching in strings](/reference/functions/regular-functions/string-search-functions) are described separately.

<Note>
  The documentation below is generated from the `system.functions` system table.
</Note>

{/*AUTOGENERATED_START*/}

<h2 id="format">
  format
</h2>

Introduced in: v20.1.0

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**

```sql theme={null}
format(pattern, s0[, s1, ...])
```

**Arguments**

* `pattern` — The format string containing placeholders. [`String`](/reference/data-types/string)
* `s0[, s1, ...]` — One or more values to substitute into the pattern. [`Any`](/reference/data-types)

**Returned value**

Returns a formatted string. [`String`](/reference/data-types/string)

**Examples**

**Numbered placeholders**

```sql title=Query theme={null}
SELECT format('{1} {0} {1}', 'World', 'Hello')
```

```response title=Response theme={null}
┌─format('{1} {0} {1}', 'World', 'Hello')─┐
│ Hello World Hello                       │
└─────────────────────────────────────────┘
```

**Implicit numbering**

```sql title=Query theme={null}
SELECT format('{} {}', 'Hello', 'World')
```

```response title=Response theme={null}
┌─format('{} {}', 'Hello', 'World')─┐
│ Hello World                       │
└───────────────────────────────────┘
```

<h2 id="overlay">
  overlay
</h2>

Introduced in: v24.9.0

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

**Syntax**

```sql theme={null}
overlay(s, replace, offset[, length])
```

**Arguments**

* `s` — The input string. [`String`](/reference/data-types/string)
* `replace` — The replacement string [`const String`](/reference/data-types/string)
* `offset` — An integer type `Int` (1-based). If `offset` is negative, it is counted from the end of the string `s`. [`Int`](/reference/data-types/int-uint)
* `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. [`Int`](/reference/data-types/int-uint)

**Returned value**

Returns a string with replacement. [`String`](/reference/data-types/string)

**Examples**

**Basic replacement**

```sql title=Query theme={null}
SELECT overlay('My father is from Mexico.', 'mother', 4) AS res;
```

```response title=Response theme={null}
┌─res──────────────────────┐
│ My mother is from Mexico.│
└──────────────────────────┘
```

**Replacement with length**

```sql title=Query theme={null}
SELECT overlay('My father is from Mexico.', 'dad', 4, 6) AS res;
```

```response title=Response theme={null}
┌─res───────────────────┐
│ My dad is from Mexico.│
└───────────────────────┘
```

<h2 id="overlayUTF8">
  overlayUTF8
</h2>

Introduced in: v24.9.0

Replace part of the string `s` 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**

```sql theme={null}
overlayUTF8(s, replace, offset[, length])
```

**Arguments**

* `s` — The input string. [`String`](/reference/data-types/string)
* `replace` — The replacement string. [`const String`](/reference/data-types/string)
* `offset` — An integer type `Int` (1-based). If `offset` is negative, it is counted from the end of the input string `s`. [`(U)Int*`](/reference/data-types/int-uint)
* `length` — Optional. 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. [`(U)Int*`](/reference/data-types/int-uint)

**Returned value**

Returns a string with replacement. [`String`](/reference/data-types/string)

**Examples**

**UTF-8 replacement**

```sql title=Query theme={null}
SELECT overlayUTF8('Mein Vater ist aus Österreich.', 'der Türkei', 20) AS res;
```

```response title=Response theme={null}
┌─res───────────────────────────┐
│ Mein Vater ist aus der Türkei.│
└───────────────────────────────┘
```

<h2 id="printf">
  printf
</h2>

Introduced in: v24.8.0

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 `%%`.
The format string can be either a constant or a column expression, allowing different format patterns per row.

**Syntax**

```sql theme={null}
printf(format[, sub1, sub2, ...])
```

**Arguments**

* `format` — The format string with `%` specifiers. [`String`](/reference/data-types/string)
* `sub1, sub2, ...` — Optional. Zero or more values to substitute into the format string. [`Any`](/reference/data-types)

**Returned value**

Returns a formatted string. [`String`](/reference/data-types/string)

**Examples**

**C++-style formatting**

```sql title=Query theme={null}
SELECT printf('%%%s %s %d', 'Hello', 'World', 2024);
```

```response title=Response theme={null}
┌─printf('%%%s %s %d', 'Hello', 'World', 2024)─┐
│ %Hello World 2024                            │
└──────────────────────────────────────────────┘
```

<h2 id="regexpQuoteMeta">
  regexpQuoteMeta
</h2>

Introduced in: v20.1.0

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.

**Syntax**

```sql theme={null}
regexpQuoteMeta(s)
```

**Arguments**

* `s` — The input string containing characters to be escaped for regex. [`String`](/reference/data-types/string)

**Returned value**

Returns a string with regex special characters escaped. [`String`](/reference/data-types/string)

**Examples**

**Escape regex special characters**

```sql title=Query theme={null}
SELECT regexpQuoteMeta('Hello. [World]? (Yes)*') AS res
```

```response title=Response theme={null}
┌─res───────────────────────────┐
│ Hello\. \[World\]\? \(Yes\)\* │
└───────────────────────────────┘
```

<h2 id="replaceAll">
  replaceAll
</h2>

Introduced in: v1.1.0

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

**Syntax**

```sql theme={null}
replaceAll(haystack, pattern, replacement)
```

**Aliases**: `replace`

**Arguments**

* `haystack` — The input string to search in. [`String`](/reference/data-types/string)
* `pattern` — The substring to find and replace. [`const String`](/reference/data-types/string)
* `replacement` — The string to replace the pattern with. [`const String`](/reference/data-types/string)

**Returned value**

Returns a string with all occurrences of pattern replaced. [`String`](/reference/data-types/string)

**Examples**

**Replace all occurrences**

```sql title=Query theme={null}
SELECT replaceAll('Hello, Hello world', 'Hello', 'Hi') AS res;
```

```response title=Response theme={null}
┌─res──────────┐
│ Hi, Hi world │
└──────────────┘
```

<h2 id="replaceOne">
  replaceOne
</h2>

Introduced in: v1.1.0

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

**Syntax**

```sql theme={null}
replaceOne(haystack, pattern, replacement)
```

**Arguments**

* `haystack` — The input string to search in. [`String`](/reference/data-types/string)
* `pattern` — The substring to find and replace. [`const String`](/reference/data-types/string)
* `replacement` — The string to replace the pattern with. [`const String`](/reference/data-types/string)

**Returned value**

Returns a string with the first occurrence of pattern replaced. [`String`](/reference/data-types/string)

**Examples**

**Replace first occurrence**

```sql title=Query theme={null}
SELECT replaceOne('Hello, Hello world', 'Hello', 'Hi') AS res;
```

```response title=Response theme={null}
┌─res─────────────┐
│ Hi, Hello world │
└─────────────────┘
```

<h2 id="replaceRegexpAll">
  replaceRegexpAll
</h2>

Introduced in: v1.1.0

Like `replaceRegexpOne` but replaces all occurrences of the pattern.
As an exception, if a regular expression worked on an empty substring, the replacement is not made more than once.

**Syntax**

```sql theme={null}
replaceRegexpAll(haystack, pattern, replacement)
```

**Aliases**: `REGEXP_REPLACE`

**Arguments**

* `haystack` — The input string to search in. [`String`](/reference/data-types/string)
* `pattern` — The regular expression pattern to find. [`const String`](/reference/data-types/string)
* `replacement` — The string to replace the pattern with, may contain substitutions. [`const String`](/reference/data-types/string)

**Returned value**

Returns a string with all regex matches replaced. [`String`](/reference/data-types/string)

**Examples**

**Replace all characters with doubled version**

```sql title=Query theme={null}
SELECT replaceRegexpAll('Hello123', '.', '\\\\0\\\\0') AS res
```

```response title=Response theme={null}
┌─res──────────────────┐
│ HHeelllloo112233     │
└──────────────────────┘
```

**Empty substring replacement example**

```sql title=Query theme={null}
SELECT replaceRegexpAll('Hello, World!', '^', 'here: ') AS res
```

```response title=Response theme={null}
┌─res─────────────────┐
│ here: Hello, World! │
└─────────────────────┘
```

<h2 id="replaceRegexpOne">
  replaceRegexpOne
</h2>

Introduced in: v1.1.0

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**

```sql theme={null}
replaceRegexpOne(haystack, pattern, replacement)
```

**Arguments**

* `haystack` — The input string to search in. [`String`](/reference/data-types/string)
* `pattern` — The regular expression pattern to find. [`const String`](/reference/data-types/string)
* `replacement` — The string to replace the pattern with, may contain substitutions. [`const String`](/reference/data-types/string)

**Returned value**

Returns a string with the first regex match replaced. [`String`](/reference/data-types/string)

**Examples**

**Converting ISO dates to American format**

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

```response title=Response theme={null}
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**

```sql title=Query theme={null}
SELECT replaceRegexpOne('Hello, World!', '.*', '\\\\0\\\\0\\\\0\\\\0\\\\0\\\\0\\\\0\\\\0\\\\0\\\\0') AS res
```

```response title=Response theme={null}
┌─res────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│ Hello, World!Hello, World!Hello, World!Hello, World!Hello, World!Hello, World!Hello, World!Hello, World!Hello, World!Hello, World! │
└────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
```

<h2 id="translate">
  translate
</h2>

Introduced in: v22.7.0

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 first character of `first` in `s` is replaced by the first character of `to`, the second character of `first` in `s` is replaced by the second 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**

```sql theme={null}
translate(s, from, to)
```

**Arguments**

* `s` — The input string to translate. [`String`](/reference/data-types/string)
* `from` — A constant ASCII string containing characters to replace. [`const String`](/reference/data-types/string)
* `to` — A constant ASCII string containing replacement characters. [`const String`](/reference/data-types/string)

**Returned value**

Returns a string with character translations applied. [`String`](/reference/data-types/string)

**Examples**

**Character mapping**

```sql title=Query theme={null}
SELECT translate('Hello, World!', 'delor', 'DELOR') AS res
```

```response title=Response theme={null}
┌─res───────────┐
│ HELLO, WORLD! │
└───────────────┘
```

**Different lengths**

```sql title=Query theme={null}
SELECT translate('clickhouse', 'clickhouse', 'CLICK') AS res
```

```response title=Response theme={null}
┌─res───┐
│ CLICK │
└───────┘
```

<h2 id="translateUTF8">
  translateUTF8
</h2>

Introduced in: v22.7.0

Like [`translate`](#translate) but assumes `s`, `from` and `to` are UTF-8 encoded strings.

**Syntax**

```sql theme={null}
translateUTF8(s, from, to)
```

**Arguments**

* `s` — UTF-8 input string to translate. [`String`](/reference/data-types/string)
* `from` — A constant UTF-8 string containing characters to replace. [`const String`](/reference/data-types/string)
* `to` — A constant UTF-8 string containing replacement characters. [`const String`](/reference/data-types/string)

**Returned value**

Returns a `String` data type value. [`String`](/reference/data-types/string)

**Examples**

**UTF-8 character translation**

```sql title=Query theme={null}
SELECT translateUTF8('Münchener Straße', 'üß', 'us') AS res;
```

```response title=Response theme={null}
┌─res──────────────┐
│ Munchener Strase │
└──────────────────┘
```