REGEXP_EXTRACT

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Syntax

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Scalar

regexp_extract(value, pattern [, group])

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Arguments

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Returns

• Type: STRING
• Possible values: Matching capture text; an empty string when nothing is captured.
• NULL behavior: Returns NULL if value or pattern is NULL. A NULL group index can make all results NULL; use a non-NULL constant index.

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Properties

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Examples

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Typical behavior

SELECT regexp_extract('a1b2', '([0-9])', 1) AS "value", regexp_extract('abc', '([0-9])', 1) AS no_match;

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Default capture group and full match

SELECT
  regexp_extract('a1b2', '([a-z])([0-9])') AS default_group,
  regexp_extract('a1b2', '([a-z])([0-9])', 0) AS full_match;

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Limitations

• Use a constant capture-group index. A group column is not evaluated independently for each row.
• Invalid regular expressions raise an error.
• Negative or out-of-range group indexes return an empty string.