Replace a Regex look ahead for Google Big Query

Question

I have some data for which i want to select the LAST VALUE BEFORE THE DELIMITER

Example- A -> B -> C -> D

In this case, i want to select "C" so i used a positive look ahead but BQ doesnt allow look aheads/behinds

Here is the Regex, (?=[^n>]-[^n-]$)[^n-]*

Can someone help me replace the look ahead?

Asked By: Mustafa Tahir

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Source

Answer 1

You don’t need any lookarounds and can use a simple regex like following and extract your needed contents from group1.

^.*->(.*)->.*$

Explanation:

^ – Matches start of text
.*-> – Matches any text greedily and second last delimiter
(.*) -> Captures the text between second last and last delimiter in group1
-> -> Matches last delimiter
.*$ -> Matches some text optionally after last delimiter and end of line

Check this demo

Answered By: Pushpesh Kumar Rajwanshi

Answer 2

Consider below options (using regex and split)

select col, 
  regexp_extract(col, r'^.*->(.*)->.*$') as extract_with_regex, 
  array_reverse(split(col, ' -> '))[offset(1)] as extract_with_split
from your_table

if applied to sample data in your question – output is

Answered By: Mikhail Berlyant

Replace a Regex look ahead for Google Big Query

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