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How to eliminate digits followed by specific string

I have quite a long regex pattern. Here is just a part of it:
string pattern = #"((?<!top=)(?<![A-Za-z])\d)+";
Given the string:
date(Account/AccountClose) gt 2019-03-25 and Brg eq '100'&$select=IdAccountCurrent&$skip=10&$top=10
It matches 2019, 03, 25, 100, 10 and 0.
I want to eliminate the last 0 from the matching result. In other words, all numbers that are followed by top= should not match.
My solution works only if I have one digit after top=.How can I achieve the desired result ?
regex101 example
UPDATE: Unfortunately, the suggested solutions are not suited for the whole pattern. I tried to make my example simple but it looks like it's imposible to do.
So my whole regex pattern is:
string pattern = #"((?<!top=)(?<![A-Za-z])\d|-|T\d+|:|\.|\+|(?<=\d)Z)+|\bfalse\b|\btrue\b|\bnull\b|'[^']+'|\(['\d][^\)]+\)";
I need to edit this pattern to eliminate all digits right after top=.
my whole example (please see the last row in this example, last 0 should not be matched)

Just add 0-9 in your regex, for forcing the digit not to be preceded by another digit:
((?<!top=)(?<![A-Za-z0-9])\d+)
See here for a demo.
But you can also just use word boundaries:
(?<!top=)\b(\d+)
See here for a demo.

You can change your regex to this where I've used \b to reject the partial matching of digits,
(?<!top=)(?<![A-Za-z])\b\d+
Demo
The way your wrote your regex ((?<!top=)(?<![A-Za-z])\d)+ will work by applying the condition on an individually and then counting one or more such characters which wouldn't have allowed using \b in your regex and hence I changed it to remove outer parenthesis and used \b\d+. Hopefully this should give you all your desired matches. Let me know if you face any issues.

Regex Group Optional

I have the following regular expression that isn't working the way I thought it would.
("^\\d{2}(?:\\d{2})?\\.\\d{2}(\\.\\d{2-4})?$");
I am trying to match a string that starts with either 2 or 4 digits, followed by a period, followed by 2 digits and then optionally another period and either 2 or 4 digits.
I would expect 33.44.4444 to work, as would 33.33 but anytime I have a string that has a 2nd period, my expression fails.
What am I doing wrong ?

Your regex is correct for what you want to do except for the {2-4} part, if you use {2,4} it will go for the 2 to 4 characters capture you're looking for.
("^\\d{2}(?:\\d{2})?\\.\\d{2}(\\.\\d{2,4})?$");
Hope it helps.

As others have pointed out the syntax {2-4} is incorrect. Use {2,4} to specify a range of occurrences. But also if you only want 2 or 4 (not 3) I would use this regex:
#"^(\d{2}|\d{4})\.\d{2}(\.(\d{2}|\d{4}))?$"

The way you expressed "either two or four digits" in the first section of your expression is correct:
\\d{2}(?:\\d{2})?
The second part does it incorrectly:
(\\.\\d{2-4})?
Copy the first part into the second to fix the problem:
("^\\d{2}(?:\\d{2})?\\.\\d{2}(\\.\\d{2}(?:\\d{2})?)?$");
Demo.

You can use this regex:
^\d{2}(?:\d{2})?\.\d{2}(?:\.\d{2}(?:\d{2})?)?$
\d{2-4} will match {2-4} text literally.
RegEx Demo

How to match a string, but only if the same string has not already been matched with or without dashes?

I have a case I'm trying to match using regular expressions.
My current expression will match a string in a certain format with or without dashes. I would like to add it to match only if the string has not been matched before, with or without the dashes. For example, take the following cases:
1. 1234-56-789-5555
2. 1234567895555
3. 0000-99-888-3333
4. 1111223334444
If the four examples above appeared in this same order in a list, document, whatever, I would want to only capture (1, 3, 4). I want to skip #2 since it was already captured by #1, but with the dashes. If #2 had of come first, I would have wanted to similarly skip #1.
Here's the current expression I'm using:
\d\d\d\d-*\d\d-*\d\d\d-*\d\d\d\d
I tried to read up on look behinds (I'm fairly inexperienced with Regex) but I only really understand that a look behind only checks if certain text is matched previously. I'm not sure if what I want can be combined with this; I only see how to check for specific text, not for the current value with/without dashes.
I'm currently doing this with C# logic, but am trying to see if it can be done purely in Regex. If it can't be done, that's fine; I'm just trying to beef up my Regex knowledge in this case.
Is this possible -- how can I accomplish this?

If you want to obtain just the first occurrence of each number (answering I want to skip #2 since it was already captured by #1, but with the dashes), you need a negative look-behind with a RegexOptions.RightToLeft and RegexOptions.Singleline options:
(?<!\b\1-?\2-?\3-?\4\b.*)\b(\d{4})-?(\d{2})-?(\d{3})-?(\d{4})\b
The \b(\d{4})-?(\d{2})-?(\d{3})-?(\d{4})\b subpattern is the number with capture groups to check for their presence regardless of the hyphens earlier in the string.
The (?<!\b\1-?\2-?\3-?\4\b.*) subpattern look-behind is checking if we have no other occurrences of the same string.
Tested at regexhero.net and in Expresso:

You can easily do this without using regex.. but if you still want to use regex for this purpose.. you can use the following to match:
(?<=((\d{4})-(\d{2})-(\d{3})-(\d{4})).*?)\2\3\4\5
And replace with '' (empty string)
Explanation:
This will match all those digits without dashes which are already captured by digits with dashes
So, in your 1,2,3 and 4.. instead of matching 1,3 and 4 types it matches type 2.. and you can replace it with '' (nothing) and you remain with 1,3, and 4
See demo here

You can use the following regex to do exactly what you want..
((?<=((\d{4})-(\d{2})-(\d{3})-(\d{4})).*?)(?!\3\4\5\6)\d{13})|(((?<=((\d{4})(\d{2})(\d{3})(\d{4})).*?)(?!\10-\11-\12-\13)((\d{4})-(\d{2})-(\d{3})-(\d{4}))))
Explanation:
((?<=((\d{4})-(\d{2})-(\d{3})-(\d{4})).*?)(?!\3\4\5\6)\d{13}) match all those \d{13} which are not previously occurred with dashes in between them (this excludes strings of type 2 in your case)
((\d{4})-(\d{2})-(\d{3})-(\d{4})) and match all of this pattern
Matches 1, 3 and 4 in your case.
See DEMO

Regex to parse formatter string

I am writing a string.Format-like method. In order to do this, I am adopting Regex to determine commands and parameters: e.g. Format(#"\m{0,1,2}", byteArr0, byteArr1, byteArr2)
For the first Regex, return 2 groups:
'\m'
'{0,1,2}'
Another Regex takes the value of '{0,1,2}' and has 3 matches:
0
1
2
These values are the indexes corresponding to the byteArr params.
This command structure is likely to grow so I'm really trying to figure this out and learn enough to be able to modify the Regex for future requirements.I would think that a single Regex would do all of the above but there is value in having 2 separate Regex(es/ices ???) expressions.
Any way, to get the first group '\m' the Regex is:
"(\\)(\w{1,1})" // I want the '{0,1,2}' group also
To get the integer matches '{0,1,2}' I was trying:
"(?<=\{)([^}]*)(?=\})"
I am having difficulty in achieving: (1) 2 groups on the first expression and (2) 3 matches on the integers within the braces delimited by a comma in the second expression.

Your first regex (\\)(\w{1,1}) can be greatly simplified.
You don't want to capture the \ separately to the m so no need to wrap them in their own sets of parenthesis.
\w{1,1} is the same as just \w.
So we have \\\w to match the first part \m.
Now to deal with the second part, really we can ignore everything other than the 0,1,2 in the example since there are no numbers elsewhere so you'd just use: \d+ and iterate through the matches.
But lets assume the example could actually be \9{1,2,3}.
Now \d+ would match the 9 so to avoid this we could use [{,](\d+)[,}]. This says capture a number that has either a , or { on the left of it and a , or } on the right.
You're right in saying that we can match the whole string with a single regex, something like this would do it:
(\\\w){((\d+),?)+}
However the problem with this is when you examine the contents of the capture groups afterwards, the last number caught by the (\d+) overwrites all the other values that were caught in there. So you'd be left with group 1: \m and group 2: 2 for your example.
With that in mind I recommend using 2 regexs:
For the 1st part: \\\w
For the numbers: I'd forget about the [{,](\d+)[,}] (and the many other ways you could do it), the cleanest way might just be to grab whatever is inside the {...} and then match with a simple \d+.
So to do this first use (\\\w)\{([^/}]+)\} to grab the \m into group 1 and the 1,2,3 into group 2, then just use \d+ on that.
FYI, your (?<=\{)([^}]*)(?=\}) works fine, but you can't but anything before the lookbehind i.e. the \\\w. In the vast majority of cases where a lookbehind can be used, you can do what you want by just using capture groups and ignoring everything else :
My regex \{([^/}]+)\} is pretty much the same as you (?<=\{)([^}]*)(?=\}) except rather than looking ahead and looking behind for the { and } I just leave them outside the capture groups that are going to be used.

Consider the following Regexes...
(^.*?)(?={.*})
\d+
Good Luck!

Regex Substring or Left Equivalent

Greetings beloved comrades.
I cannot figure out how to accomplish the following via a regex.
I need to take this format number 201101234 and transform it to 11-0123401, where digits 3 and 4 become the digits to the left of the dash, and the remaining five digits are inserted to the right of the dash, followed by a hardcoded 01.
I've tried http://gskinner.com/RegExr, but the syntax just defeats me.
This answer, Equivalent of Substring as a RegularExpression, sounds promising, but I can't get it to parse correctly.
I can create a SQL function to accomplish this, but I'd rather not hammer my server in order to reformat some strings.
Thanks in advance.

You can try this:
var input = "201101234";
var output = Regex.Replace(input, #"^\d{2}(\d{2})(\d{5})$", "${1}-${2}01");
Console.WriteLine(output); // 11-0123401
This will match:
two digits, followed by
two digits captured as group 1, followed by
five digits captured as group 2
And return a string which replaces that matched text with
group 1, followed by
a literal hyphen, followed by
group 2, followed by
a literal 01.
The start and end anchors ( ^ / $ ) ensure that if the input string does not exactly match this pattern, it will simply return the original string.

If you can use custom C# scripts, you may want to use Substring instead:
string newStr = string.Format("{0}-{1}01", old.Substring(2,2), old.Substring(4));

I don't think you really need a regex here. Substring would be better. But still if you want regex only, you can use this:
string newString = Regex.Replace(input, #"^\d{2}(\d{2})(\d+)$", "$1-${2}01");
Explanation:
^\d{2} // Match first 2 digits. Will be ignored
(\d{2}) // Match next 2 digits. Capture it in group 1
(\d+)$ // Match rest of the digits. Capture it in group 2
Now, the required digits, are in group 1 and 2, which you use in the replacement string.

Do you even SQL? Pull some levers and stuff.