Question

I have 2 tables, table 1 has a field which contains prefixes for companies.

The values retrieved from table 1 need to be used to get records from table 2 (based on the prefixes returned).

I coded below to do a startswith to demo what I need done, however what I need to do is build a dynamic starswith clause.

I know the code below wont compile, just putting it out there to show what I would like to accomplish.

//*   This pulls list of prefixes from Table 1

var xrfPrefixes = from xx in XrfPrefixes
 select new
 {
   xxx.CompanyPrefix
 };

//* Get list of prefixes
string PrefixList = "";
foreach (var xxx in xrfJobPrefix)
{
    PrefixList = PrefixList + xxx.FirmJobPrefix + ",";
}

//* Get back Matching records from table 2
var results = from p in Orders.Where(p => p.OrdCust.StartsWith(PrefixList))
select p;

Sample Data in Table 1 (Customers):

• Row 1: Customer_Prefix char(50) value = “ab1, ab2”
• Row 2: Customer_Prefix char(50) value = “xy1”
• Row 3: Customer_Prefix char(50) value = “xy2”

Sample data in table 2 (orders):

• row 1: customer_name char(50) value = “ab1filler”
• row 2: customer_name char(50) value = “ab2filler”
• row 3: customer_name char(50) value = “ab3filler”
• row 4: customer_name char(50) value = “xy1filler”
• row 5: customer_name char(50) value = “xy2filler”
• row 6: customer_name char(50) value = “xy3filler”

Based on the customer_prefixes in the Customers table, the records from Orders Table returned would be Rows 1,2,4 & 5

Answer 1

1. Create a PrefixList. Don’t do it as a list of comma-separated strings, do it as a real List<String>. That means you have to split comma-separated values (using String.Split, for example):

   var prefixList = new List<string>();
   foreach (var xxx in xrfJobPrefix) 
   { 
       prefixList.AddRange(xxx.FirmJobPrefix.Split(',').Select(pre => pre.Trim())); 
   } 
   

2. After you have a PrefixList, you can do a simple LINQ query as follows:

   var results = from p in orders
                 from pre in prefixList
                 where p.OrdCust.StartsWith(pre)) 
                 select p;