Join SQL Server tables on a like statement

Question

I am hoping this isn't a repeat. I've checked the searches and I can't seem to find a clear answer to this.

I have a table that has it's primary key set to be a UniqueIdentifier. I also have another table that has a varchar column that basically contains a url with a query string that contains guids from my first table.

So my 2 tables are like:

StateTable

StateID                                  StateName
EB06F84C-15B9-4397-98AD-4A63DA2A238E     Active

URLTable

URL
page.aspx?id=EB06F84C-15B9-4397-98AD-4A63DA2A238E

What I'm trying to do is join together URLTable and StateTable ON the value of StateID is contained in URL of URL table. I haven't really figured out the join. I've even tried just selecting the one table and tried to filter by the values in StateTable. I've tried doing something like this:

SELECT  *
FROM URLTable
WHERE     EXISTS
    (SELECT  *
     FROM  StateTable
     WHERE URL LIKE '%' + StateID + '%')

Even that doesn't work because it says I'm comparing uniqueidentifier and varchar.

Is there any way to join 2 tables using a like command and where the like command isn't comparing 2 incompatible variables?

Thank you!!

UPDATE: Let me add some additional things I should have mentioned. The query is for the purposes of building analytics reports. The tables are part of a CMS analytics package... so updating or changing the table structure is not an option.

Secondly, these tables see a very high amount of traffic since they're capturing site analytics... so performance is very much an issue. The 3rd thing is that in my example, I said id= but there may be multiple values such as id=guid&user=guid&date=date.

UPDATE 2: One more thing I just realized to my horror is that sometimes the query string has the dashes removed from the GUID.. and sometimes not.. so unless I"m mistaken, I can't cast the substring to Uniqueidentifier. Can anyone confirm? sigh. I did get it to work using

REPLACE('-','',CONVERT(varchar(50), a.AutomationStateId))

but now I'm very much worried about performance issues with this since the URL's table is very large. This might be the nature of the beast, though, unless there's anything I can do.

Answer 1

Cast StateID to a compatible type, e.g.

WHERE URL LIKE '%' + CONVERT(varchar(50), StateID) + '%'

or

WHERE URL LIKE N'%' + CONVERT(nvarchar(50), StateID) + N'%'

if URL is nvarchar(...)

EDIT

As pointed out in another answer, this could result in poor performance on large tables. The LIKE combined with a CONVERT will result in a table scan. This may not be a problem for small tables, but you should consider splitting the URL into two columns if performance becomes a problem. One column would contain 'page.aspx?id=' and the other the UNIQUEIDENTIFIER. Your query could then be optimized much more easily.