I have been working on some legacy code in our application that detects certain keywords in the text of an SQL stored procedure by using Regex and I have found a bug that I can't quite correct due to my limited knowledge of Regex.
Basically the regex that I currently have works in all but one case:
(?<=\n\s*)(?<!with.*[\s\S]*)as
It should return a match on this version of a stored procedure:
ALTER PROCEDURE [dbo].[p_obj_name_with_something]
#username [nvarchar](100) = null,
#id [int] = null,
#mode [int] = 0
AS
/*-------------------------------------------------------------------------
However it shouldn't for this version, but it currently does return a match:
ALTER PROCEDURE [dbo].[p_obj_name_with_something]
#username [nvarchar](100) = null,
#id [int] = null,
#mode [int] = 0
WITH EXECUTE AS CALLER
AS
/*-------------------------------------------------------------------------
I want a match when the keyword WITH isn't found before the AS keyword, but it will allow the word within the name or parameters of the stored procedure.
The way I think the detection would work is if the keyword WITH has whitespace (or a newline) either side of it, but I can't quite figure out the regex syntax.
Any suggestions?
Check out this site:
http://www.mikesdotnetting.com/Article/46/CSharp-Regular-Expressions-Cheat-Sheet
notice the lines:
\s Matches any white space including space, tab, form-feed, etc. Equivalent to "[ \f\n\r\t\v]".
[^xyz] A negative character set. Matches any character not enclosed. For example, "[^abc]" matches the "p" in "plain".
so.....
[\s]+[[WITH]|[with][\s]+[[^AS]|[^as]]*
breakdown of it:
[\s]+ is the whitespace on either side
[[with]|[WITH][ case insensitive check for with
[[^AS]|[^as]]* case insensitive check that will match as long as AS or as isnt there
hope this helps
Even though it isn't a real answer, I found the easier way to do this was to enforce some naming convention rules in our stored procedures and modify the 20 or so that violated the rules.
Indeed, this is a case when Regex is not the solution!
Related
So I had this code working for a few months already, lets say I have a table called Categories, which has a string column called name, so I receive a string and I want to know if any category was mentioned (a mention occur when the string contains the substring: #name_of_a_category), the approach I follow for this was something like below:
categories.select { |category_i| content_received.downcase.match(/##{category_i.downcase}/)}
That worked pretty well until today suddenly started to receive an exception unmatched close parenthesis, I realized that the categories names can contain special chars so I decided to not consider special chars or spaces anymore (don't want to add restrictions to the user and at the same time don't want to deal with those cases so the policy is just to ignore it).
So the question is there a clean way of removing these special chars (maintaining the #) and matching the string (don't want to modify the data just ignore it while looking for mentions)?
You can also use
prep_content_received = content_received.gsub(/[^\w\s]|_/,'')
p categories.select { |c|
prep_content_received.match?(/\b#{c.gsub(/[^\w\s]|_/, '').strip()}\b/i)
}
See the Ruby demo
Details:
The prep_content_received = content_received.gsub(/[^\w\s]|_/,'') creates a copy of content_received with no special chars and _. Using it once reduced overhead if there are a lot of categories
Then, you iterate over the categories list, and each time check if the prep_content_received matches \b (word boundary) + category with all special chars, _ and leading/trailing whitespace stripped from it + \b in a case insensitive way (see the /i flag, no need to .downcase).
So after looking around I found some answers on the platform but nothing with my specific requirements (maybe I missed something, if so please let me know), and this is how I fix it for my case:
content_received = 'pepe is watching a #comedy :)'
categories = ['comedy :)', 'terror']
temp_content = content_received.downcase
categories.select { |category_i| temp_content.gsub(/[^\sa-zA-Z0-9]/, '#' => '#').match?(/##{category_i.downcase.
gsub(/[^\sa-zA-Z0-9]/, '')}/) }
For the sake of the example, I reduced the categories to a simple array of strings, basically the first gsub, remove any character that is not a letter or a number (any special character) and replace each # with an #, the second gsub is a simpler version of the first one.
You can test the snippet above here
I made a regex which inserts a space where ever there is any of the characters
-:\*_/;, present for example JET*AIRWAYS\INDIA/858701/IDBI 05/05/05;05:05:05 a/c should beJET* AIRWAYS\ INDIA/ 858701/ IDBI 05/05/05; 05:05:05 a/c
The regex I used is (?!a\/c|w\/d|m\/s|s\/w|m\/o)(\D-|\D:|\D\*|\D_|\D\\|\D\/|\D\;)
I have added some words exceptions like a/c w/d etc. \D conditions given to avoid date/time values getting separated, but this created an issue, the numbers followed by the above mentioned characters never get split.
My requirement is
1. Insert a space after characters -:\*_/;,
2. but date and time should not get split which may have / :
3. need exception on words like a/c w/d
The following is the full code
Private Function formatColon(oldString As String) As String
Dim reg As New RegExp: reg.Global = True: reg.Pattern = "(?!a\/c|w\/d|m\/s|s\/w|m\/o)(\D-|\D:|\D\*|\D_|\D\\|\D\/|\D\;)" '"(\D:|\D/|\D-|^w/d)"
Dim newString As String: newString = reg.Replace(oldString, "$1 ")
formatColon = XtraspaceKill(newString)
End Function
I would use 3 replacements.
Replace all date and time special characters with a special macro that should never be found in your text, e.g. for 05/15/2018 4:06 PM, something based on your name:
05MANUMOHANSLASH15MANUMOHANSLASH2018 4MANUMOHANCOLON06 PM
You can encode exceptions too, like this:
aMANUMOHANSLASHc
Now run your original regex to replace all special characters.
Finally, unreplace the macros MANUMOHANSLASH and MANUMOHANCOLON.
Meanwhile, let me tell you why this is complicated in a single regex.
If trying to do this in a single regex, you have to ask, for each / or :, "Am I a part of a date or time?"
To answer that, you need to use lookahead and lookbehind assertions, the latter of which Microsoft has finally added support for.
But given a /, you don't know if you're between the first and second, or second and third parts of the date. Similar for time.
The number of cases you need to consider will render your regex unmaintainably complex.
So please just use a few separate replacements :-)
I am looking for a regex to select the text which falls outside of underscore characters.
Sample text:
PartIWant_partINeedIgnored_morePartsINeedIgnored_PartIwant
Basically I need to be able to select the first keyword which is always before the first underscore and the last keyword which is always after the last underscore. As an additional complexity, there case also be texts which have no underscore at all, these need to be selected completely as well.
The best I got yet was this expression:
^((?! *\_[^)]*\_ *).)*
which is only yielding me the first part, not the second and it has no support for the non-underscore yet at all.
This regex is used in a tool which monitors our http traffic, which means I can only 'select' the part I need but can't invoke functions or replace logic.
Thanks!
Use JavaScript string function split(). Check below example.
var t = "PartIWant_partINeedIgnored_morePartsINeedIgnored_PartIwant";
var arr = t.split('_');
console.log(arr);
//Access the required parts like this
console.log(arr[0] + ' ' + arr[arr.length - 1]);
Perhaps something like this:
/(^[^_]+)|([^_]+$)/g
That is, match either:
^[^_]+ the beginning of the string followed by non-underscores, or
[^_]+$ non-underscores followed by the end of the string.
var regex = /(^[^_]+)|([^_]+$)/g
console.log("A_b_c_D".match(regex)) // ["A", "D"]
console.log("A_b_D".match(regex)) // ["A", "D"]
console.log("A_D".match(regex)) // ["A", "D"]
console.log("AD".match(regex)) // ["AD"]
I'm not sure if you should use a regex here. I think splitting the string at underscore, and using the first and last element of the resulting array might be faster, and less complicated.
Trivial with .replace:
str.replace(/_.*_/, '')
// "PartIWantPartIwant"
With matching, you'd need to be selecting and concatenating groups:
parts = str.match(/^([^_]*).*?([^_]*)$/)
parts[1] + parts[2]
// "PartIWantPartIwant"
EDIT
This regex is used in a tool which monitors our http traffic, which means I can only 'select' the part I need but can't invoke functions or replace logic.
This is not possible: a regular expression cannot match a discontinuous span.
I have a string
IsNull(VSK1_DVal.RuntimeSUM,0),
I need to remove IsNull part, so the result would be
VSK1_DVal.RuntimeSUM,
I'm absolute new to RegEx, but it wouldn't be a problem, if not one thing :
VSK1 is dynamic part, can be any combination of A-Z,0-9 and any length. How to replace strings with RegEx? I use MSSQL 2k5, i think it uses general set of RegEx rules.
EDIT : I forgot to say, that I'm doing replacement in SSMS Query window's Replace Box (^H) - not building RegEx query
br
marius
here's a regex that should work:
[^(]+\(([^,]+),[^)]\)
Then use $1 capture group to extract the part that you need.
I did a sanity check in ruby:
orig = "IsNull(VSK1_DVal.RuntimeSUM,0),"
regex = /[^(]*\(([^,]+),[^)]\)/
result = orig.sub(regex){$1} # result => VSK1_DVal.RuntimeSUM,
It gets trickier if you have a prefix that you want to retain. Like if you have this:
"somestuff = IsNull(VSK1_DVal.RuntimeSUM,0),"
In this case, you need someway to identify the start of the pattern. Maybe you can use '=' to identify the start of the pattern? If so, this should work:
orig = "somestuff = IsNull(VSK1_DVal.RuntimeSUM,0),"
regex = /=\s*\w+\(([^,]+),[^)]\)/
result = orig.sub(regex){$1} # result => somestuff = VSK1_DVal.RuntimeSUM,
But then the case where you don't have an equals sign will fail. Maybe you can use 'IsNull' to identify the start of the pattern? If so, try this (note the '/i' representing case insensitive matching):
orig = "somestuff = isnull(VSK1_DVal.RuntimeSUM,0),"
regex = /IsNull\(([^,]+),[^)]\)/i
result = orig.sub(regex){$1} # result => somestuff = VSK1_DVal.RuntimeSUM,
/IsNULL\((A-Z0-9+),0\)/
Then pick group match number 1.
Here's a very useful site: http://www.regexlib.com/RETester.aspx
They have a tester and a cheatsheet that are very useful for quick testing of this sort.
I tested the solution by Dave and it works fine except it also removes the trailing comma you wanted retained. Minor thing to fix.
Try this:
IsNULL\((.*,)0\)
You say in your question
I use MSSQL 2k5, i think it uses
general set of RegEx rules.
This is not true unless you enable CLR and compile and install an assembly. You can use its native pattern matching syntax and LIKE for this as below.
WITH T(C) AS
(
SELECT 'IsNull(VSK1_DVal.RuntimeSUM,0),' UNION ALL
SELECT 'IsNull(VSK1_DVal.RuntimeSUM,123465),' UNION ALL
SELECT 'No Match'
)
SELECT SUBSTRING(C,8,1+LEN(C)-8-CHARINDEX(',',REVERSE(C),2))
FROM T
WHERE C LIKE 'IsNull(%,_%),'
Is it possible to write a regular expression that matches all strings that does not only contain numbers? If we have these strings:
abc
a4c
4bc
ab4
123
It should match the four first, but not the last one. I have tried fiddling around in RegexBuddy with lookaheads and stuff, but I can't seem to figure it out.
(?!^\d+$)^.+$
This says lookahead for lines that do not contain all digits and match the entire line.
Unless I am missing something, I think the most concise regex is...
/\D/
...or in other words, is there a not-digit in the string?
jjnguy had it correct (if slightly redundant) in an earlier revision.
.*?[^0-9].*
#Chad, your regex,
\b.*[a-zA-Z]+.*\b
should probably allow for non letters (eg, punctuation) even though Svish's examples didn't include one. Svish's primary requirement was: not all be digits.
\b.*[^0-9]+.*\b
Then, you don't need the + in there since all you need is to guarantee 1 non-digit is in there (more might be in there as covered by the .* on the ends).
\b.*[^0-9].*\b
Next, you can do away with the \b on either end since these are unnecessary constraints (invoking reference to alphanum and _).
.*[^0-9].*
Finally, note that this last regex shows that the problem can be solved with just the basics, those basics which have existed for decades (eg, no need for the look-ahead feature). In English, the question was logically equivalent to simply asking that 1 counter-example character be found within a string.
We can test this regex in a browser by copying the following into the location bar, replacing the string "6576576i7567" with whatever you want to test.
javascript:alert(new String("6576576i7567").match(".*[^0-9].*"));
/^\d*[a-z][a-z\d]*$/
Or, case insensitive version:
/^\d*[a-z][a-z\d]*$/i
May be a digit at the beginning, then at least one letter, then letters or digits
Try this:
/^.*\D+.*$/
It returns true if there is any simbol, that is not a number. Works fine with all languages.
Since you said "match", not just validate, the following regex will match correctly
\b.*[a-zA-Z]+.*\b
Passing Tests:
abc
a4c
4bc
ab4
1b1
11b
b11
Failing Tests:
123
if you are trying to match worlds that have at least one letter but they are formed by numbers and letters (or just letters), this is what I have used:
(\d*[a-zA-Z]+\d*)+
If we want to restrict valid characters so that string can be made from a limited set of characters, try this:
(?!^\d+$)^[a-zA-Z0-9_-]{3,}$
or
(?!^\d+$)^[\w-]{3,}$
/\w+/:
Matches any letter, number or underscore. any word character
.*[^0-9]{1,}.*
Works fine for us.
We want to use the used answer, but it's not working within YANG model.
And the one I provided here is easy to understand and it's clear:
start and end could be any chars, but, but there must be at least one NON NUMERICAL characters, which is greatest.
I am using /^[0-9]*$/gm in my JavaScript code to see if string is only numbers. If yes then it should fail otherwise it will return the string.
Below is working code snippet with test cases:
function isValidURL(string) {
var res = string.match(/^[0-9]*$/gm);
if (res == null)
return string;
else
return "fail";
};
var testCase1 = "abc";
console.log(isValidURL(testCase1)); // abc
var testCase2 = "a4c";
console.log(isValidURL(testCase2)); // a4c
var testCase3 = "4bc";
console.log(isValidURL(testCase3)); // 4bc
var testCase4 = "ab4";
console.log(isValidURL(testCase4)); // ab4
var testCase5 = "123"; // fail here
console.log(isValidURL(testCase5));
I had to do something similar in MySQL and the following whilst over simplified seems to have worked for me:
where fieldname regexp ^[a-zA-Z0-9]+$
and fieldname NOT REGEXP ^[0-9]+$
This shows all fields that are alphabetical and alphanumeric but any fields that are just numeric are hidden. This seems to work.
example:
name1 - Displayed
name - Displayed
name2 - Displayed
name3 - Displayed
name4 - Displayed
n4ame - Displayed
324234234 - Not Displayed