c# - How to simulate regular expressions in LINQ-to-SQL

Question

I have a database table with customer account numbers. Within the same table are test accounts that don't match the production formatting: say, 'A1111' is production but 'JTest' is not. I have the Regex that will pull only my production accounts. I need a specific compiled query to pull only the production accounts. The query gives me a customer count by region and date; and concept counts within each region:

        getCustomerDistribution = CompiledQuery.Compile<DataContext, String, DateTime, IEnumerable<ServerLoad>>(
            (context, region, processDate) => (from cust in context.GetTable<tbl_CustomerDistro>()
                                               where cust.ProcessedDate.Date == processDate.Date
                                               where cust.Region == region
                                               where Regex.IsMatch(cust.AcctNum, ProductionMask)
                                               group cust by new
                                               {
                                                   cust.Region,
                                                   cust.Concept
                                               } into custDistro
                                               orderby custDistro.Key.Region
                                               select new CustomerDistro
                                               (
                                                   custDistro.Key.Region,
                                                   custDistro.Key.Concept,
                                                   custDistro
                                                    .Where(c => c.Concept == custDistro.Key.Concept)
                                                    .Select(c => c.Concept).Count()
                                               )));

Problem is that I get the following message at run-time:

Method 'Boolean IsMatch(System.String, System.String)' has no supported translation to SQL.

I was looking at a user defined func:

static Func<striing, bool> IsProduction = (AcctNum) => Regex.IsMatch(AcctNum, ProductionMask);

This doesn't work either. I don't want to iterate the records that are retrieved to further filter unless there is just no other way to do this.

Is there a way to do this with Predicate Builder?

Update:

Another option I think would be to use:

where SqlMethods.Like (cust.AcctNum, ProductionMask)

However, my ProductionMask is written for Regex:

^[B,G]d{4}$

Is there a way to do this with the SqlMethods.Like(...)?

Update 2:

This is a very slow running query. I have 3 regions that this query runs against and the record counts & return times are:
263: 903ms
342: 822ms
146: 711ms

Answer 1

I changed the query to use the following in place of the Regex.IsMatch:

where SqlMethods.Like(cust.Acct, ProductionMask)  

where ProductionMask = "[bBgG][0-9][0-9][0-9][0-9]"

the equivalent RegEx is: ^[B,G]d{4}$

If anyone sees that the 2 masks should not produce the same results, please let me know...