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Function to test for valid email format

Posted on 2003-11-14
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Last Modified: 2012-08-13
Strange i couldn't find a similar question already answered...seems a common task.

I want to test a field's value to see if it's a valid email format.

thankx
--steve...
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Question by:juststeve
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14 Comments
 
LVL 32

Expert Comment

by:jadedata
ID: 9750533
Hey juststeve!

  This depends on what you consider a valid email address.  Generally I would think this includes a "@" and a "." in it.  Would these be your only requirements?

  Public Function ValidEmailAddr(sEmailAddr as String) as Boolean
    if _
      instr(sEmailAddr,"@")>1 and _
      instr(sEmailAddr,".")>3 _
    then
      ValidEmailAddr=True
    endif
  end function

I guess you could also test the last three characters for com/net/org/edu etc.

regards
Jack
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Author Comment

by:juststeve
ID: 9750604
thanks jadedata...how would that code look in TSQL?
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LVL 32

Expert Comment

by:jadedata
ID: 9750896
you'll need to get a second opinion on this one,  I thought I was in a VBA flavor forum... sorry.
(but the logic is good, even if the code isn't...)
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LVL 75

Expert Comment

by:Anthony Perkins
ID: 9750919
PatIndex('%@%.___%', emailaddress) > 0
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LVL 75

Expert Comment

by:Anthony Perkins
ID: 9750952
Actually assuming the service level (COM, NET, EDU, ORG, etc) is 3 characters (not always the case) and the @ cannot be the first or last character before the "." than this would be more accurate:

Patindex('_%@%_.___%', 'emailaddress')

Anthony
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Expert Comment

by:jadedata
ID: 9750963
thanx for bailin' me out acperkins!
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Accepted Solution

by:
Anthony Perkins earned 200 total points
ID: 9750966
That last % should not be there, nor should the quotes arround the column:

Patindex('_%@%_.___', emailaddress)

Anthony
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LVL 6

Assisted Solution

by:acampoma
acampoma earned 150 total points
ID: 9750981
Create Function CheckEmail (@EmailAddress varchar (100)) Returns Bit
as
Begin
Declare @IsEmail Bit
if Charindex('@',@EmailAddress)>1 and Charindex('.',@EmailAddress)>3  Begin
      set @IsEmail= 1
      End
else Begin
      set @IsEmail= 0
      End
Return @IsEmail
End      
   
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LVL 6

Expert Comment

by:acampoma
ID: 9751003
the above example :
select Patindex('_%@%_.___', 'acampoma@mb.sympatico.ca')
will fail with my email address
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LVL 75

Expert Comment

by:Anthony Perkins
ID: 9751063
acampoma,

Not sure if you read my comments:
"Actually assuming the service level (COM, NET, EDU, ORG, etc) is 3 characters (not always the case)"

If you are dealing with 2 or 3 characters than it is as simple as changing to:

select Patindex('_%@%_.__%', emailaddress)

Anthony
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LVL 6

Expert Comment

by:acampoma
ID: 9751112
you are Correct acperkins . And your solution is much simpler than mine.
Cheers!
I was not very familiar with the patindex function. I see that it will come to use in the future
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LVL 75

Expert Comment

by:Anthony Perkins
ID: 9751207
But actually you bring up a good point and my code was not checking correctly for subdomains (and therefore multiple "."), here is a better solution:

Patindex('_%@%_', emailaddress) > 0 And (Patindex('__.%', Reverse(emailaddress)) > 0 Or Patindex('___.%', Reverse(emailaddress)))

If you want to test it, try is as follows:

Declare @EmailAddress sysname; Set @Email = 'somebody@subdomain.domain.com'
Select Patindex('_%@%_', @Email) * (Patindex('__.%', Reverse(@EmailAddress)) + Patindex('___.%', Reverse(@Email)))

The truth of the matter, is that pattern matching in SQL Server is quite primitive and you are better offr doing this in the front-end or wait for Yukon and Regular Expressions <g>

Anthony
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LVL 19

Assisted Solution

by:Dexstar
Dexstar earned 150 total points
ID: 9757451
juststeve:

> I want to test a field's value to see if it's a valid email format.

As an extra measure, I would add a constraint on the e-mail field in the table.  Create a rule with the following definition:
      ((@value IS NULL) OR (@value  LIKE '%@%.%'))

Hope That Helps,
Dex*
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Author Comment

by:juststeve
ID: 9758431
thankx to all
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