Regular Expressions 101

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/
SELECT(.+)FROM (\w)+ WHERE (.+) REGION (\w+)
/
g
SELECT
matches the characters SELECT literally (case sensitive)
1st Capturing Group
(.+)
.
matches any character (except for line terminators)
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
FROM
matches the characters FROM literally (case sensitive)
2nd Capturing Group
(\w)+
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
A repeated capturing group will only capture the last iteration. Put a capturing group around the repeated group to capture all iterations or use a non-capturing group instead if you're not interested in the data
\w matches any word character (equivalent to [a-zA-Z0-9_])
WHERE
matches the characters WHERE literally (case sensitive)
3rd Capturing Group
(.+)
.
matches any character (except for line terminators)
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
REGION
matches the characters REGION literally (case sensitive)
4th Capturing Group
(\w+)
\w
matches any word character (equivalent to [a-zA-Z0-9_])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
Global pattern flags
g modifier: global. All matches (don't return after first match)
Your regular expression does not match the subject string.Try launching the debugger to find out why.

Regular Expression
No Match

/
/
g

Test String