how can I make a Regex to match prefix and multiple suffixes at same time?

I've encountered this problem: I need to clean some corrupted data that has the following pattern:

VALUES ( 1', NULL, 'Smith', 'Jackson',...
VALUES ( 2', 'jon@doe', 'John', 'Doe',...

Basically, I need to remove the extra ', for that I first need to match it...

So I came up with this

(?<=VALUES \(  \d+)(.*')(?=(, '[a-zA-Z])||(^NULL,$))

Unfortunately, it's not matching anything, the \d+ is specially problematic.

Any idea how I can isolate the 1', 2', ... (only the ' after the number that can have N digits) and be able to match the prefix for 'string or NULL

Solution

One option is to use

\b(VALUES\s*\(\s*\d+)'(?=,\s*(?:NULL|'[a-zA-Z]))

Explanation

\b A word boundary
( Capture group 1 (to be used in the replacement keeping this part)
- VALUES\s*\(\s*\d+ Match VALUES, ( and then match 1+ digits
) Close group 1
' Match the ' that you want to remove
(?=,\s*(?:NULL|'[a-zA-Z]) Positive lookahead to make sure that directly to the right is a comma followed by NULL or ' and a char a-z

Regex demo

In the replacement use group 1.

Output

VALUES (  1, NULL, 'Smith', 'Jackson',...
VALUES (  2, 'jon@doe', 'John', 'Doe',...