Categories:: String functions (regular expressions)

REGEXP_REPLACE¶

Returns the subject with the specified pattern — or all occurrences of the pattern — either removed or replaced by a replacement string.

Syntax¶

 REGEXP_REPLACE( <subject> ,
                 <pattern>
                   [ , <replacement>
                     [ , <position>
                       [ , <occurrence>
                         [ , <parameters> ]
                       ]
                     ]
                   ]
)

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Arguments¶

Required:

subject

The string to search for matches.

pattern

Pattern to match.

For guidelines on specifying patterns, see String functions (regular expressions).

Optional:

replacement

String that replaces the substrings matched by the pattern. If an empty string is specified, the function removes all matched patterns and returns the resulting string.

Default: '' (empty string).

position

Number of characters from the beginning of the string where the function starts searching for matches. The value must be a positive integer.

Default: 1 (the search for a match starts at the first character on the left)

occurrence

Specifies which occurrence of the pattern to replace. If 0 is specified, all occurrences are replaced.

Default: 0 (all occurrences)

parameters

String of one or more characters that specifies the parameters used for searching for matches. Supported values:

Parameter	Description
`c`	Case-sensitive matching
`i`	Case-insensitive matching
`m`	Multi-line mode
`e`	Extract submatches
`s`	Single-line mode POSIX wildcard character `.` matches `\n`

Default: c

For more information, see Specifying the parameters for the regular expression.

Returns¶

Returns a value of type VARCHAR.

If no matches are found, returns the original subject.

Returns NULL if any argument is NULL.

Usage notes¶

The replacement string can contain backreferences to capture groups; for example, sub-expressions of the pattern. A capture group is a regular expression that is enclosed within parentheses (( )). The maximum number of capture groups is nine.

Backreferences match expressions inside a capture group. Backreferences have the form n where n is a value from 0 to 9, inclusive, which refers to the matching instance of the capture group. For more information, see Examples (in this topic).

Parentheses (( )) and square brackets ([ ]) currently must be double-escaped to parse them as literal strings.

The example below shows how to remove parentheses:

SELECT REGEXP_REPLACE('Customers - (NY)','\\(|\\)','') AS customers;

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+----------------+
| CUSTOMERS      |
|----------------|
| Customers - NY |
+----------------+

For additional usage notes, see the General usage notes for regular expression functions.

Collation details¶

Arguments with collation specifications currently aren’t supported.

Examples¶

The following example replaces all spaces in the string with nothing (that is, all spaces are removed):

SELECT REGEXP_REPLACE('It was the best of times, it was the worst of times',
                      '( ){1,}',
                      '') AS result;

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+------------------------------------------+
| RESULT                                   |
|------------------------------------------|
| Itwasthebestoftimes,itwastheworstoftimes |
+------------------------------------------+

The following example matches the string times and replaces it with the string days. Matching begins at the first character in the string and replaces the second occurrence of the substring:

SELECT REGEXP_REPLACE('It was the best of times, it was the worst of times',
                      'times',
                      'days',
                      1,
                      2) AS result;

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+----------------------------------------------------+
| RESULT                                             |
|----------------------------------------------------|
| It was the best of times, it was the worst of days |
+----------------------------------------------------+

The following example uses backreferences to rearrange the string firstname middlename lastname as lastname, firstname middlename and insert a comma between lastname and firstname:

SELECT REGEXP_REPLACE('firstname middlename lastname',
                      '(.*) (.*) (.*)',
                      '\\3, \\1 \\2') AS name_sort;

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+--------------------------------+
| NAME_SORT                      |
|--------------------------------|
| lastname, firstname middlename |
+--------------------------------+

The remaining examples use the data in the following table:

CREATE OR REPLACE TABLE regexp_replace_demo(body VARCHAR(255));

INSERT INTO regexp_replace_demo values
  ('Hellooo World'),
  ('How are you doing today?'),
  ('the quick brown fox jumps over the lazy dog'),
  ('PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS');

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The following example inserts the character * between every character of the subject, including the beginning and the end, using an empty group (()), which finds a match between any two characters:

SELECT body,
       REGEXP_REPLACE(body, '()', '*') AS replaced
  FROM regexp_replace_demo;

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+---------------------------------------------+-----------------------------------------------------------------------------------------+
| BODY                                        | REPLACED                                                                                |
|---------------------------------------------+-----------------------------------------------------------------------------------------|
| Hellooo World                               | *H*e*l*l*o*o*o* *W*o*r*l*d*                                                             |
| How are you doing today?                    | *H*o*w* *a*r*e* *y*o*u* *d*o*i*n*g* *t*o*d*a*y*?*                                       |
| the quick brown fox jumps over the lazy dog | *t*h*e* *q*u*i*c*k* *b*r*o*w*n* *f*o*x* *j*u*m*p*s* *o*v*e*r* *t*h*e* *l*a*z*y* *d*o*g* |
| PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS     | *P*A*C*K* *M*Y* *B*O*X* *W*I*T*H* *F*I*V*E* *D*O*Z*E*N* *L*I*Q*U*O*R* *J*U*G*S*         |
+---------------------------------------------+-----------------------------------------------------------------------------------------+

The following example removes all of the vowels by replacing them with nothing, regardless of their order or case:

SELECT body,
       REGEXP_REPLACE(body, '[aeiou]', '', 1, 0, 'i') AS replaced
  FROM regexp_replace_demo;

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+---------------------------------------------+----------------------------------+
| BODY                                        | REPLACED                         |
|---------------------------------------------+----------------------------------|
| Hellooo World                               | Hll Wrld                         |
| How are you doing today?                    | Hw r y dng tdy?                  |
| the quick brown fox jumps over the lazy dog | th qck brwn fx jmps vr th lzy dg |
| PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS     | PCK MY BX WTH FV DZN LQR JGS     |
+---------------------------------------------+----------------------------------+

The following example removes all words that contain the lowercase letter o from the subject by matching a word boundary (\b), followed by zero or more word characters (\S), the letter o, and then zero or more word characters until the next word boundary:

SELECT body,
       REGEXP_REPLACE(body, '\\b(\\S*)o(\\S*)\\b') AS replaced
  FROM regexp_replace_demo;

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+---------------------------------------------+-----------------------------------------+
| BODY                                        | REPLACED                                |
|---------------------------------------------+-----------------------------------------|
| Hellooo World                               |                                         |
| How are you doing today?                    |  are   ?                                |
| the quick brown fox jumps over the lazy dog | the quick   jumps  the lazy             |
| PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS     | PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS |
+---------------------------------------------+-----------------------------------------+

The following example replaces all words that contain the lowercase letter o, swapping the letters in front of and behind the first instance of o, and replacing the o with the character sequence @@:

SELECT body,
       REGEXP_REPLACE(body, '\\b(\\S*)o(\\S*)\\b', '\\2@@\\1') AS replaced
  FROM regexp_replace_demo;

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+---------------------------------------------+-------------------------------------------------+
| BODY                                        | REPLACED                                        |
|---------------------------------------------+-------------------------------------------------|
| Hellooo World                               | @@Helloo rld@@W                                 |
| How are you doing today?                    | w@@H are u@@y ing@@d day@@t?                    |
| the quick brown fox jumps over the lazy dog | the quick wn@@br x@@f jumps ver@@ the lazy g@@d |
| PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS     | PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS         |
+---------------------------------------------+-------------------------------------------------+

The following example is the same as the previous example, but the replacement starts at position 3 in the subject:

SELECT body,
       REGEXP_REPLACE(body, '\\b(\\S*)o(\\S*)\\b', '\\2@@\\1', 3) AS replaced
  FROM regexp_replace_demo;

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+---------------------------------------------+-------------------------------------------------+
| BODY                                        | REPLACED                                        |
|---------------------------------------------+-------------------------------------------------|
| Hellooo World                               | He@@lloo rld@@W                                 |
| How are you doing today?                    | How are u@@y ing@@d day@@t?                     |
| the quick brown fox jumps over the lazy dog | the quick wn@@br x@@f jumps ver@@ the lazy g@@d |
| PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS     | PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS         |
+---------------------------------------------+-------------------------------------------------+

The following example is the same as the previous example, but only the third occurrence is replaced, starting at position 3 in the subject:

SELECT body,
       REGEXP_REPLACE(body, '\\b(\\S*)o(\\S*)\\b', '\\2@@\\1', 3, 3) AS replaced
  FROM regexp_replace_demo;

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+---------------------------------------------+----------------------------------------------+
| BODY                                        | REPLACED                                     |
|---------------------------------------------+----------------------------------------------|
| Hellooo World                               | Hellooo World                                |
| How are you doing today?                    | How are you doing day@@t?                    |
| the quick brown fox jumps over the lazy dog | the quick brown fox jumps ver@@ the lazy dog |
| PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS     | PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS      |
+---------------------------------------------+----------------------------------------------+

The following example is the same as the previous example, but it uses case-insensitive matching:

SELECT body,
       REGEXP_REPLACE(body, '\\b(\\S*)o(\\S*)\\b', '\\2@@\\1', 3, 3, 'i') AS replaced
  FROM regexp_replace_demo;

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+---------------------------------------------+----------------------------------------------+
| BODY                                        | REPLACED                                     |
|---------------------------------------------+----------------------------------------------|
| Hellooo World                               | Hellooo World                                |
| How are you doing today?                    | How are you doing day@@t?                    |
| the quick brown fox jumps over the lazy dog | the quick brown fox jumps ver@@ the lazy dog |
| PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS     | PACK MY BOX WITH FIVE DOZEN R@@LIQU JUGS     |
+---------------------------------------------+----------------------------------------------+