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Asked: 2026-05-27T06:43:57+00:00

I have a table which contains Email Domains separated by semi-colons. Domain —— gmail.com;googlemail.com

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I have a table which contains Email Domains separated by semi-colons.

Domain
------
gmail.com;googlemail.com
hotmail.com;hotmail.co.uk;live.co.uk

I am currently running the following SQL:

SELECT [Id]
  FROM [DomainGroup]
 WHERE [Domain] LIKE '%' + (SELECT RIGHT('anemail@gmail.com', CHARINDEX('@', REVERSE('anemail@gmail.com')) - 1)) + '%'

Although this is working, I was thinking that maybe using PATINDEX would be better, from both performance and readability. The email address is actually a variable, but I’ve put it in to show what I’m trying to achieve.

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1 Answer

  1. Editorial Team

    I think the performance benefit of PATINDEX vs LIKE is at best ambiguous, particularly in your case given that normalizing the delimited values to individual rows in an indexed column would give more of a performance boost than anything else.

    If you can’t change design & want to use PATINDEX, then I would pre-compute the pattern;

    declare @emaildomain varchar(128) = 'anemail@gmail.com'
set @emaildomain = '%;' + stuff(@emaildomain, 1, charindex('@', @emaildomain), '')  + ';%'

    Then use that in the where clause;

    where patindex(@emaildomain, ';' + [Domain] + ';') > 0

    (I padded with ; delimiters so aaa@bbb.com would not match aaabbb.com;)

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