Merge pull request #218871 from ssabat/master

Updated regexExtract on how index behaves

Author: prmerger-automator[bot]

articles/data-factory/data-flow-expressions-usage.md

@@ -1925,7 +1925,7 @@ ___
 
 ### <code>regexExtract</code>
 <code><b>regexExtract(<i>&lt;string&gt;</i> : string, <i>&lt;regex to find&gt;</i> : string, [<i>&lt;match group 1-based index&gt;</i> : integral]) => string</b></code><br/><br/>
-Extract a matching substring for a given regex pattern. The last parameter identifies the match group and is defaulted to 1 if omitted. Use `<regex>`(back quote) to match a string without escaping.  
+Extract a matching substring for a given regex pattern. The last parameter identifies the match group and is defaulted to 1 if omitted. Use `<regex>`(back quote) to match a string without escaping. Index 0  returns all matches. Without match groups, index 1 and above won’t return any result. 
 * ``regexExtract('Cost is between 600 and 800 dollars', '(\\d+) and (\\d+)', 2) -> '800'``  
 * ``regexExtract('Cost is between 600 and 800 dollars', `(\d+) and (\d+)`, 2) -> '800'``  
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