我将如何在LINQ2SQL中编写它？

Question

I am slowly porting over an app from MySQL to use Linq2Sql - but one query has stumped me a bit.

SELECT * FROM Pages WHERE DomainID = @reportid AND (PageContent REGEXP 'display:[ \\t]*none') > 0 ORDER BY URL ASC

Any ideas on how I would write something like this with Linq2SQL? Its the REGEXP bit thats got me stumped?

Answer 1

There is no way built in to LINQ to SQL, but you have a couple of other choices. The first is to load your strings in as in-memory objects which you can apply Regex functions to . I'm not a big fan of this since it looks like you're potentially getting some very big strings to match against.

The second option is to leverage SQL CLR as described here . This effectively lets you create a stored procedure that gets linked to a CLR method that you create. Whenever you call the method in a LINQ to SQL context, it gets converted to a stored procedure call. Then you use a query like this:

var q = from p in context.Pages
        where p.DomainId == reportId && 
              RegExMatch(p.PageContent, "display\:[ \t]*none")
        select p;

Answer 2

Why not use LINQ to return items that match on reportid and that contain 'display:', to minimise the amount of data being returned from the server, and then use regex on client side to filter that list down?

var query = Pages.Where( p => p.DomainId == 1 && p.PageContent.IndexOf("display:") > 0).OrderBy( o => o.URL );

var regex = new Regex(@"display\:[\t]*none");

foreach (var page in query)
{
    if( regex.IsMatch(page.PageContent) )
    {
        // Do whatever...                    
    }                    
}