Snowflake and Regular Expressions - issue when implementing known good expression in SF - snowflake-cloud-data-platform

I'm looking for some assistance in debugging a REGEXP_REPLACE() statement.
I have been using an online regular expressions editor to build expressions, and then the SF regexp_* functions to implement them. I've attempted to remain consistent with the SF regex implementation, but I'm seeing an inconsistency in the returned results that I'm hoping someone can explain :)
My intent is to replace commas within the text (excluding commas with double-quoted text) with a new delimiter (#^#).
Sample text string:
"Foreign Corporate Name Registration","99999","Valuation Research",,"Active Name",02/09/2020,"02/09/2020","NEVADA","UNITED STATES",,,"123 SOME STREET",,"MILWAUKEE","WI","53202","UNITED STATES","123 SOME STREET",,"MILWAUKEE","WI","53202","UNITED STATES",,,,,,,,,,,,
RegEx command and Substitution (working in regex101.com):
([("].*?["])*?(,)
\1#^#
regex101.com Result:
"Foreign Corporate Name Registration"#^#"99999"#^#"Valuation Research"#^##^#"Active Name"#^#02/09/2020#^#"02/09/2020"#^#"NEVADA"#^#"UNITED STATES"#^##^##^#"123 SOME STREET"#^##^#"MILWAUKEE"#^#"WI"#^#"53202"#^#"UNITED STATES"#^#"123 SOME STREET"#^##^#"MILWAUKEE"#^#"WI"#^#"53202"#^#"UNITED STATES"#^##^##^##^##^##^##^##^##^##^##^##^#
When I try and implement this same logic in SF using REGEXP_REPLACE(), I am using the following statement:
SELECT TOP 500
A.C1
,REGEXP_REPLACE((A."C1"),'([("].*?["])*?(,)','\\1#^#') AS BASE
FROM
"<Warehouse>"."<database>"."<table>" AS A
This statement returns the result for BASE:
"Foreign Corporate Name Registration","99999","Valuation Research",,"Active Name",02/09/2020,"02/09/2020","NEVADA","UNITED STATES",,,"123 SOME STREET",,"MILWAUKEE","WI","53202","UNITED STATES","123 SOME STREET",,"MILWAUKEE","WI","53202","UNITED STATES"#^##^##^##^##^##^##^##^##^##^##^##^#
As you can see when comparing the results, the SF result set is only replacing commas at the tail-end of the text.
Can anyone tell me why the results between regex101.com and SF are returning different results with the same statement? Is my expression non-compliant with the SF implementation of RegEx - and if yes, can you tell me why?
Many many thanks for your time and effort reading this far!
Happy Wednesday,
Casey.

The use of .*? to achieve lazy matching for regexing is limited to PCRE, which Snowflake does not support. To see this, in regex101.com, change your 'flavor" to be anything other than PCRE (PHP); you will see that your ([("].*?["])*?(,) regex no longer achieves what you are expecting.
I believe that this will work for your purposes:
REGEXP_REPLACE(A.C1,'("[^"]*")*,','\\1#^#')

Related

Identify all strings in SQL Server code (red color - like in SSMS)

I was not able to solve this by myself so I hope I didn't miss any similar post here and I'm not wasting your time.
What I want is to identify (get a list) of all strings used in SQL Server code.
Example:
select 'WordToCatch1' as 'Column1'
from Table1
where Column2 = 'WordToCatch2'
If you put above code to SSMS all three words in apostrophes will be red but only words 'WordToCatch1' and 'WordToCatch2' are "real" strings used in code.
My goal is to find all those "real" strings in any code.
For example if I will have stored procedure 10k rows long it would be impossible to search them manually so I want something what will find all those "real" strings for me and return a list of them or something.
Thanks in advance!
The trouble is, Column1 is nothing particular different compared to WordToCatch1 and WordToCatch2 - not unless you parse the SQL yourself. You could modify your query to take the quotes away from Column1 and it will show up coloured black.
I guess a simple regex will show up all identifiers after an AS keyword, which would be easier than fully parsing SQL, if all the unwanted strings are like that, and its not just an example.

SQL Contains exact phrase

I try to implement a search-mechanism with "CONTAINS()" on a SQL Server 2014.
I've read here https://technet.microsoft.com/en-us/library/ms142538%28v=sql.105%29.aspx and in the book "Pro Full-Text Search in SQL Server 2008" that I need to use double quotes to search an exact phrase.
But e.q. if I use this CONTAINS(*, '"test"') I receive results containing words like "numerictest" also. If I try CONTAINS(*, '" test "') it is the same. I've noticed, that there are less results as if I would search with CONTAINS(*, '*test*') for a prefix, sufix search, so there is definitely a delta between the searches.
I didn't expect the "numerictest" in the first statement. Is there an explanation for this behaviour?
I have been wracking my brain about a very similar problem and I recently found the solution.
In my case I was searching full text fields for "#username" but using CONTAINS(body, "#username") returned just "username" as well. I wanted it to strictly match with the # sign.
I could use LIKE "%#username%" but the query took over a minute which was unacceptable so I kept looking.
With the help of some people in a chat room they suggested using both CONTAINS and LIKE. So:
SELECT TOP 25 * FROM table WHERE
CONTAINS(body, "#username") AND body LIKE "%#username%";
this worked perfectly for me because the contains pulls both username and #username records and then the LIKE filters out the ones with the # sign. Queries take 2-3 seconds now.
I know this is an old question but I came across it in my searching so having the answer I thought I would post it. I hope this helps.
Contains(*,'"test"') will only match full words of "test" as you expect.
Contains(*,'" test "') same as above
Contains(*,'"*test*"') will actually do a PREFIX ONLY search, basically strips out any special characters at the start of word and only uses the 2nd *.
You cannot do POSTFIX searches using full text search.
My concern lies with the Contains(*) part, this will search for any full text cataloged items in that entire row. Without seeing the data it is hard to tell but my guess is that another column in that row you think is bad is actually matching on "test" somewhere.

Regular expression in SQL Server 2005+

I am stuck with a regular expression in SQL server 2005+, i.e. I need a regular expression to validate a first name (which allows only alphabets,whitespaces and a .(dot)).
I tried with below query
SELECT PATINDEX('%[A-Z]%[a-z]%[.]%','John H. Wilson') as VALIDFIRSTNAME
But, this also fails in some cases. I'm unable to find a clear regular expression. Any assistance would be very much appreciated.
I have used patindex to recognise the given pattern. If the string doesn't match the pattern, then It should give 0 else it should give 1 or >1.
Thanks in advance.
You can't match mentioned condition with available patterns.
Try to follow this way.

Regular Expression in Visual Studio Find & Replace - multiple spaces between search terms

I require a regular expression for the Visual Studio Search and Replace functionality, as follows:
Search for the following term: sectorkey in (
There could be multiple spaces between each of the above 3 search terms, or even multiple line breaks/carriage returns.
The search term is looking for SQL statements that have hard-coded SectorKey values inside a SQL in statement. These need to be replaced with a SQL join statement - this will be done manually.
The little arrow to the right of the Find What box is your friend and can help you with the vagaries of the MS regex syntax.
Newline is represented by \n, so you can just do sectorkey( |\n)+in( |\n)+\( (You need to escape the open paren in your search expression, since that's used in grouping.)
I believe :Wh+ is what you want. The Visual Studio regex flavor is very strange; you'll tend to get better results if you consult the official reference. Expertise with "mainstream" regexes tends to be more of a handicap than a help when it comes to VS.
You can use \s+ to search for one or more adjacent whitespace characters (including tab, CR, LF etc), so your regex would presumably end up looking something like sectorkey\s+in\s+\(.
Edit...
As Joe points out in his comment, it seems that Visual Studio doesn't support \s in Find/Replace expressions, in which case you'll probably need to use something like [\n:b] instead. The regex would then become sectorkey[\n:b]+in[\n:b]+\(.

How do you get leading wildcard full-text searches to work in SQL Server?

Note: I am using SQL's Full-text search capabilities, CONTAINS clauses and all - the * is the wildcard in full-text, % is for LIKE clauses only.
I've read in several places now that "leading wildcard" searches (e.g. using "*overflow" to match "stackoverflow") is not supported in MS SQL. I'm considering using a CLR function to add regex matching, but I'm curious to see what other solutions people might have.
More Info: You can add the asterisk only at the end of the word or phrase. - along with my empirical experience: When matching "myvalue", "my*" works, but "(asterisk)value" returns no match, when doing a query as simple as:
SELECT * FROM TABLENAME WHERE CONTAINS(TextColumn, '"*searchterm"');
Thus, my need for a workaround. I'm only using search in my site on an actual search page - so it needs to work basically the same way that Google works (in the eyes on a Joe Sixpack-type user). Not nearly as complicated, but this sort of match really shouldn't fail.
Workaround only for leading wildcard:
store the text reversed in a different field (or in materialised view)
create a full text index on this column
find the reversed text with an *
SELECT *
FROM TABLENAME
WHERE CONTAINS(TextColumnREV, '"mrethcraes*"');
Of course there are many drawbacks, just for quick workaround...
Not to mention CONTAINSTABLE...
The problem with leading Wildcards: They cannot be indexed, hence you're doing a full table scan.
It is possible to use the wildcard "*" at the end of the word or phrase (prefix search).
For example, this query will find all "datab", "database", "databases" ...
SELECT * FROM SomeTable WHERE CONTAINS(ColumnName, '"datab*"')
But, unforutnately, it is not possible to search with leading wildcard.
For example, this query will not find "database"
SELECT * FROM SomeTable WHERE CONTAINS(ColumnName, '"*abase"')
To perhaps add clarity to this thread, from my testing on 2008 R2, Franjo is correct above. When dealing with full text searching, at least when using the CONTAINS phrase, you cannot use a leading , only a trailing functionally. * is the wildcard, not % in full text.
Some have suggested that * is ignored. That does not seem to be the case, my results seem to show that the trailing * functionality does work. I think leading * are ignored by the engine.
My added problem however is that the same query, with a trailing *, that uses full text with wildcards worked relatively fast on 2005(20 seconds), and slowed to 12 minutes after migrating the db to 2008 R2. It seems at least one other user had similar results and he started a forum post which I added to... FREETEXT works fast still, but something "seems" to have changed with the way 2008 processes trailing * in CONTAINS. They give all sorts of warnings in the Upgrade Advisor that they "improved" FULL TEXT so your code may break, but unfortunately they do not give you any specific warnings about certain deprecated code etc. ...just a disclaimer that they changed it, use at your own risk.
http://social.msdn.microsoft.com/Forums/ar-SA/sqlsearch/thread/7e45b7e4-2061-4c89-af68-febd668f346c
Maybe, this is the closest MS hit related to these issues... http://msdn.microsoft.com/en-us/library/ms143709.aspx
One thing worth keeping in mind is that leading wildcard queries come at a significant performance premium, compared to other wildcard usages.
Note: this was the answer I submitted for the original version #1 of the question before the CONTAINS keyword was introduced in revision #2. It's still factually accurate.
The wildcard character in SQL Server is the % sign and it works just fine, leading, trailing or otherwise.
That said, if you're going to be doing any kind of serious full text searching then I'd consider utilising the Full Text Index capabilities. Using % and _ wild cards will cause your database to take a serious performance hit.
Just FYI, Google does not do any substring searches or truncation, right or left. They have a wildcard character * to find unknown words in a phrase, but not a word.
Google, along with most full-text search engines, sets up an inverted index based on the alphabetical order of words, with links to their source documents. Binary search is wicked fast, even for huge indexes. But it's really really hard to do a left-truncation in this case, because it loses the advantage of the index.
As a parameter in a stored procedure you can use it as:
ALTER procedure [dbo].[uspLkp_DrugProductSelectAllByName]
(
#PROPRIETARY_NAME varchar(10)
)
as
set nocount on
declare #PROPRIETARY_NAME2 varchar(10) = '"' + #PROPRIETARY_NAME + '*"'
select ldp.*, lkp.DRUG_PKG_ID
from Lkp_DrugProduct ldp
left outer join Lkp_DrugPackage lkp on ldp.DRUG_PROD_ID = lkp.DRUG_PROD_ID
where contains(ldp.PROPRIETARY_NAME, #PROPRIETARY_NAME2)
When it comes to full-text searching, for my money nothing beats Lucene. There is a .Net port available that is compatible with indexes created with the Java version.
There's a little work involved in that you have to create/maintain the indexes, but the search speed is fantastic and you can create all sorts of interesting queries. Even indexing speed is pretty good - we just completely rebuild our indexes once a day and don't worry about updating them.
As an example, this search functionality is powered by Lucene.Net.
Perhaps the following link will provide the final answer to this use of wildcards: Performing FTS Wildcard Searches.
Note the passage that states: "However, if you specify “Chain” or “Chain”, you will not get the expected result. The asterisk will be considered as a normal punctuation mark not a wildcard character. "
If you have access to the list of words of the full text search engine, you could do a 'like' search on this list and match the database with the words found, e.g. a table 'words' with following words:
pie
applepie
spies
cherrypie
dog
cat
To match all words containing 'pie' in this database on a fts table 'full_text' with field 'text':
to-match <- SELECT word FROM words WHERE word LIKE '%pie%'
matcher = ""
a = ""
foreach(m, to-match) {
matcher += a
matcher += m
a = " OR "
}
SELECT text FROM full_text WHERE text MATCH matcher
% Matches any number of characters
_ Matches a single character
I've never used Full-Text indexing but you can accomplish rather complex and fast search queries with simply using the build in T-SQL string functions.
From SQL Server Books Online:
To write full-text queries in
Microsoft SQL Server 2005, you must
learn how to use the CONTAINS and
FREETEXT Transact-SQL predicates, and
the CONTAINSTABLE and FREETEXTTABLE
rowset-valued functions.
That means all of the queries written above with the % and _ are not valid full text queries.
Here is a sample of what a query looks like when calling the CONTAINSTABLE function.
SELECT RANK , * FROM TableName ,
CONTAINSTABLE (TableName, *, '
"*WildCard" ') searchTable WHERE
[KEY] = TableName.pk ORDER BY
searchTable.RANK DESC
In order for the CONTAINSTABLE function to know that I'm using a wildcard search, I have to wrap it in double quotes. I can use the wildcard character * at the beginning or ending. There are a lot of other things you can do when you're building the search string for the CONTAINSTABLE function. You can search for a word near another word, search for inflectional words (drive = drives, drove, driving, and driven), and search for synonym of another word (metal can have synonyms such as aluminum and steel).
I just created a table, put a full text index on the table and did a couple of test searches and didn't have a problem, so wildcard searching works as intended.
[Update]
I see that you've updated your question and know that you need to use one of the functions.
You can still search with the wildcard at the beginning, but if the word is not a full word following the wildcard, you have to add another wildcard at the end.
Example: "*ildcar" will look for a single word as long as it ends with "ildcar".
Example: "*ildcar*" will look for a single word with "ildcar" in the middle, which means it will match "wildcard". [Just noticed that Markdown removed the wildcard characters from the beginning and ending of my quoted string here.]
[Update #2]
Dave Ward - Using a wildcard with one of the functions shouldn't be a huge perf hit. If I created a search string with just "*", it will not return all rows, in my test case, it returned 0 records.

Resources