check string in two tables

Question

1.00/5 (1 vote)

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SQL-Server-2008R2

Hi Experts,

I have 2 tables (customers, users) each of them has [Email] Field, no common fields to join.
I want to be able to check if a given email exists in either one, something like:

SQL

select Id from customers where customers.email='email' or user.email='email'
OR
return true if @email exists in (customers or users)

looking for the correct syntax.

Thanks in advance!
Samira

Posted 26-Aug-15 3:41am

Samira Radwan

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3 solutions

Solution 3

Another way is to use pivot table this way:

SQL

SELECT TableName, [Customers], [User] 
FROM (
    SELECT 'Customers' AS TableName, ID, Email
    FROM Customers
    UNION ALL
    SELECT 'User' AS TableName, ID, Email
    FROM User
) AS DT
PIVOT (MAX(ID) FOR TableName IN ([Customers], [User])) AS PT
WHERE Email = @email

Posted 26-Aug-15 9:46am

Maciej Los

Solution 1

best use a couple of simple "not exists"

SQL

declare @email nvarchar(max)
set @email = 'me@mine.com'

IF  not exists (select * from customers where customers.email=@email) 
and not exists (select * from users where users.email=@email) 
  return 1
else
  return 0

hope that helps ^_^
Andy

Posted 26-Aug-15 3:51am

Andy Lanng

Updated 26-Aug-15 5:25am

v3

Comments

Samira Radwan 26-Aug-15 10:35am

Thanks Andy, I think your query has syntax error. I had to add if before the first (not) but still. Incorrect syntax near ')' the last brackets. Any idea why?

Andy Lanng 26-Aug-15 10:38am

Oh - copy-paste error - The second line should read users.email=@email
:P
No need for an if. pointless to say "if(this) return true else return false". Should just be able to return 'this' ('this' being the logic query). I could be wrong though :/

CHill60 26-Aug-15 10:41am

Not convinced return works like that in sql

Andy Lanng 26-Aug-15 10:47am

me neither, but hopefully the OP will work it out and let us know ^_^

Herman<T>.Instance 26-Aug-15 10:41am

Why declare nvarchar(max) if only 11 chars are needed?

Andy Lanng 26-Aug-15 10:46am

nvarchar(max) always uses the least space it can. If you want to limit yourself then you can use a number. I usually don't bother because it doesn't take any extra space.
This is not the case in SQL2000 btw where there was no MAX

CHill60 26-Aug-15 17:17pm

Virtual 5 for this comment :-)

Samira Radwan 26-Aug-15 11:18am

(return + not) not working, syntax error :)

Andy Lanng 26-Aug-15 11:26am

wait a second. Is there even a true / false type? there's a bit but that's 1/0

I have altered my solution (actually tested it now ^_^)

Samira Radwan 26-Aug-15 12:02pm

That's better :)
I had to modify your answer and remove (not).
Thank you!

Andy Lanng 26-Aug-15 12:06pm

If you remove "NOT" then you must change "AND" to "OR". It's the law of logical absolutes. You could have just changes the return values :P

Samira Radwan 26-Aug-15 12:27pm

I did ^_^

Andy Lanng 26-Aug-15 12:31pm

Ah, cool. Phew! Looks like CHill has a more elegant solution anyway ^_^

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CHill60 · Accepted Answer · 2015-08-26T04:45:00

Solution 2

An alternative would be to union the email addresses e.g.

SQL

DECLARE @Result int

--Dummy data
declare @tbl1 table (id1 int identity(1,1), email1 varchar(30))
declare @tbl2 table (id2 int identity(1,1), email2 varchar(30))
insert into @tbl1  values('email1'),('email2'),('email3')
insert into @tbl2  values('email4'),('email2'),('email5')

if exists (select top 1 * from (select email1 from @tbl1 union select email2 from @tbl2) t where email1=@email)
    set @Result= 1
else
    set @Result= 0

 return @Result

Posted 26-Aug-15 4:45am

CHill60

Comments

Samira Radwan 26-Aug-15 12:03pm

Thanks! that works.

Andy Lanng 26-Aug-15 12:27pm

Alright, smarty-pants. You get a 5* :P

Samira Radwan 26-Aug-15 12:29pm

got 5* ^_^

Maciej Los 26-Aug-15 15:47pm

Very interesting, Caroline. +5!
Please, see my solution ;)