T-SQL: Find column match within a string (LIKE but different) - tsql

Question

Server: SQL Server 2008 R2
I apologize in advance, as I'm not sure of the best way to verbalize the question. I'm receiving a string of email addresses and I need to see if, within that string, any of the addresses exist as a user already. The query that obviously doesn't work is shown below, but hopefully it helps to clarify what I'm looking for:
SELECT f_emailaddress
FROM tb_users
WHERE f_emailaddress LIKE '%user1#domain.com,user2#domain.com%'
I was hoping SQL had an "InString" operator, that would check for matches "within the string", but I my Google abilities must be weak today.
Any assistance is greatly appreciated. If there simply isn't a way, I'll have to dig in and do some work in the codebehind to split each item in the string and search on each one.
Thanks in advance,
Beems

Answer 1

Split the input string and use IN clause
to split the CSV to rows use this.
SELECT Ltrim(Rtrim(( Split.a.value('.', 'VARCHAR(100)') )))
FROM (SELECT Cast ('<M>'
+ Replace('user1#domain.com,user2#domain.com', ',', '</M><M>')
+ '</M>' AS XML) AS Data) AS A
CROSS APPLY Data.nodes ('/M') AS Split(a)
Now use the above query in where clause.
SELECT f_emailaddress
FROM tb_users
WHERE f_emailaddress IN(SELECT Ltrim(Rtrim(( Split.a.value('.', 'VARCHAR(100)') )))
FROM (SELECT Cast ('<M>'
+ Replace('user1#domain.com,user2#domain.com', ',', '</M><M>')
+ '</M>' AS XML) AS Data) AS A
CROSS APPLY Data.nodes ('/M') AS Split(a))
Or use can use Inner Join
SELECT f_emailaddress
FROM tb_users A
JOIN (SELECT Ltrim(Rtrim(( Split.a.value('.', 'VARCHAR(100)') )))
FROM (SELECT Cast ('<M>'
+ Replace('user1#domain.com,user2#domain.com', ',', '</M><M>')
+ '</M>' AS XML) AS Data) AS A
CROSS APPLY Data.nodes ('/M') AS Split(a)) B
ON a.f_emailaddress = b.f_emailaddress

Answer 2

You first need to split the CSV list into a temp table and then use that to INNER JOIN with your existing table, as that will act as a filter.
You cannot use CONTAINS unless you have created a Full Text index on that table and column, which I doubt is the case here.
For example:
CREATE TABLE #EmailAddresses (Email NVARCHAR(500) NOT NULL);
INSERT INTO #EmailAddress (Email)
SELECT split.Val
FROM dbo.Splitter(#IncomingListOfEmailAddresses);
SELECT usr.f_emailaddress
FROM tb_users usr
INNER JOIN #EmailAddresses tmp
ON tmp.Email = usr.f_emailaddress;
Please note that the reference to "dbo.Splitter" is a placeholder for whatever string splitter you already have or might get. Please do not use any splitter that makes use of a WHILE loop. The best options are either the SQLCLR- or XML- based ones. The XML-based ones are generally fast but do have some issues with encoding if the string to be split has special XML characters such as &, <, or ". If you want a quick and easy SQLCLR-based splitter, you can download the Free version of the SQL# library (which I am the creator of, but this feature is in the free version) which contains String_Split and String_Split4k (for when the input is always <= 4000 characters).

Answer 3

SQL has a CONTAINS and an IN function. You can use either of those to accomplish your task. Click on either for more information via MSDNs website! Hope this helps.
CONTAINS
CONTAINS will look to see if any values in your data contain the entire string you provided. Kind of similar in presentations to LIKE '%myValue%';
SELECT f_emailaddress
FROM tb_users
WHERE CONTAINS (f_emailaddress, 'user1#domain.com');
IN
IN will return matches for any values in the provided comma delimited list. They need to be exact matches however. You can't provide partial terms.
SELECT f_emailaddress
FROM tb_users
WHERE f_emailaddress IN ('user1#domain.com','user2#domain.com')
As far as splitting each of the values out into separate strings, have a look at the StackOverflow question found HERE. This might point you in the proper direction.

Answer 4

You can try like this(not tested).
Before using this, make sure that you have created a Full Text index on that table and column.
Replace your comma with AND then
SELECT id,email
FROM t
where CONTAINS(email, 'user1#domain.com and user2#domain.com');

Answer 5

--prepare temp table for testing
DECLARE #tb_users AS TABLE
(f_emailaddress VARCHAR(100))
INSERT INTO #tb_users
( f_emailaddress)
VALUES ( 'user1#domain.com' ),
( 'user2#domain.com' ),
( 'user3#domain.com' ),
( 'user4#domain.com' )
--Your query
SELECT f_emailaddress
FROM #tb_users
WHERE 'user1#domain.com,user2#domain.com' LIKE '%' + f_emailaddress + '%'