Question

I want to insert multiple email into SQL Server table cell and before inserting them I need check whether the values are already there or not.

For more clarification

Row_id        EMAIL_ID
  1           [e-mail],[e-mail], [e-mail]
  2           [e-mail],[e-mail]

Now If I insert [e-mail],[e-mail], it will show that value is duplicated.

I did this

select EMAIL_ID
from TR_DEMO
INNER JOIN dbo.split('[e-mail],[e-mail]', ',') s
ON s.items IN (select items from dbo.split(EMAIL_ID, ',') )

Function

CREATE FUNCTION [dbo].[Split]
(
    @String varchar(8000), 
    @Delimiter char(1)
)       
returns @temptable TABLE (items varchar(8000))       
as       
begin       
    declare @idx int       
    declare @slice varchar(8000)       

    select @idx = 1       
        if len(@String)<1 or @String is null  return       

    while @idx!= 0       
    begin       
        set @idx = charindex(@Delimiter,@String)       
        if @idx!=0       
            set @slice = left(@String,@idx - 1)       
        else       
            set @slice = @String       

        if(len(@slice)>0)  
            insert into @temptable(Items) values(rtrim(ltrim(@slice)))       

        set @String = right(@String,len(@String) - @idx)       
        if len(@String) = 0 break       
    end   
return       
end 

It works fine, but query is slow while checking the records around 100000

Can we do the same by wildcard or something else?

Answer 1

There is a trick you can use for comparing against a comma-separated list. First, you’ll want to split your input list. Then for each item, you’ll want to check the following:

SELECT EMAIL_ID
  FROM TR_DEMO
 WHERE ','+EMAIL_ID+',' LIKE '%,[e-mail],%'

Demo: http://www.sqlfiddle.com/#!3/6dd71/2

Here’s another example using your SPLIT method to generate the items:

    SELECT EMAIL_ID
      FROM TR_DEMO T
INNER JOIN dbo.split('[e-mail],[e-mail]', ',') s
               ON ','+T.EMAIL_ID+',' LIKE '%,'+s.items+',%'

http://www.sqlfiddle.com/#!3/a9a7b/1