techdocsmith commented on code in PR #16862:
URL: https://github.com/apache/druid/pull/16862#discussion_r1718781988
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docs/querying/sql-functions.md:
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@@ -1834,28 +1924,90 @@ Returns the rank with gaps for a row within a window.
For example, if two rows t
## REGEXP_EXTRACT
-`REGEXP_EXTRACT(<CHARACTER>, <CHARACTER>, [<INTEGER>])`
+Apply regular expression `pattern` to `expr` and extract the Nth capture
group. If `N` is unspecified or zero, returns the first substring that matches
the pattern. Returns `null` if there is no matching pattern.
-**Function type:** [Scalar, string](sql-scalar.md#string-functions)
+* **Syntax:** `REGEXP_EXTRACT(expr, pattern[, N])`
+* **Function type:** Scalar, string
+
+<details><summary>Example</summary>
-Applies a regular expression to the string expression and returns the _n_th
match.
+The following example uses regular expressions to find city names inside the
`OriginCityName` column from the `flight-carriers` datasource by matching what
comes before the comma.
+
+```sql
+SELECT
+ "OriginCityName" AS "origin_city",
+ REGEXP_EXTRACT("OriginCityName", '([^,]+)', 0) AS "pattern_match"
+FROM "flight-carriers"
+LIMIT 1
+```
+
+Returns the following:
+
+| `origin_city` | `pattern_match` |
+| -- | -- |
+| `San Juan, PR` | `San Juan`|
+
+</details>
+
+[Learn more](sql-scalar.md#string-functions)
## REGEXP_LIKE
-`REGEXP_LIKE(<CHARACTER>, <CHARACTER>)`
+Returns `true` if the regular expression `pattern` finds a match in `expr`.
Returns `false` otherwise.
-**Function type:** [Scalar, string](sql-scalar.md#string-functions)
+* **Syntax:** `REGEXP_LIKE(expr, pattern)`
+* **Function type:** Scalar, string
+
+<details><summary>Example</summary>
-Returns true or false signifying whether the regular expression finds a match
in the string expression.
+The following example returns `true` when the `OriginCityName` column from
`flight-carriers` has a city name with a space in the name.
+
+```sql
+SELECT
+ "OriginCityName" AS "origin_city",
+ REGEXP_LIKE("OriginCityName", '[A-Za-z]+\s[A-Za-z]+') AS "pattern_found"
+FROM "flight-carriers"
+LIMIT 2
+```
+
+Returns the following:
+
+| `origin_city` | `pattern_found` |
+| -- | -- |
+| `San Juan, PR` | `true` |
+| `Boston, MA` | `false` |
+
+</details>
+
+[Learn more](sql-scalar.md#string-functions)
## REGEXP_REPLACE
-`REGEXP_REPLACE(<CHARACTER>, <CHARACTER>, <CHARACTER>)`
+Replaces all occurrences of a regular expression in a string expression with a
replacement string. The replacement string may refer to capture groups using
`$1`, `$2`, etc.
Review Comment:
```suggestion
Replaces all occurrences of a regular expression in a string expression with
a replacement string. Refer
to capture groups in the replacement string using `$group` syntax. For
example: `$1` or `$2`.
```
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