linq中where子句中的sql case语句

Question

Here is my string sql query, but i am unable to convert it to linq as it contains cases based where clause, any help will be appreciated.

if (StrClientID.Equals("008"))
                   objdbhims.Query += "   and (( case when t.external_org is null then d.clientid='008' end) or t.external_org in ('008','-1'))";
               else if (StrClientID.Equals("006"))
                   objdbhims.Query += " and (t.external_org<>'008' or (case when t.external_org is null then d.clientid='" + StrClientID + "' end))";
               else
                   objdbhims.Query += " and d.clientid='"+StrClientID+"'";

Answer 1

You may add a lot of Where clauses to your IQueryable object before fetching data from DB. For example:

var data = SomeContext.MyTable.Where(x => x.SomeField == someValue);
if (someCondition) 
{
  // Something like your 1st if clause
  data = data.Where(x => (x.SomeField2 != null && x.SomeField3 == "someText") || new[] { "001", "002" }.Contains(x.SomeField2));
}

var result = data.ToList();

Answer 2

I solved it myself after struggling alot with this solution by using ternary operator, i just put 1==1 in the else part to get rid of error:

string[] arr = new string[] {"008","-1"};

string ClientID = HttpContext.Current.Session["ClientID"].ToString();

&& (
                                ClientID == "008"
                             ? (t.external_org == null 
                                               ? d.clientid =="008" : 1 == 1)
                                               || (arr.Contains(t.external_org))


                                : ClientID == "006"
                             ? (t.external_org == null
                                               ? d.clientid == ClientID : 1 == 1)
                                               || (t.external_org != "008")

                        : d.clientid == ClientID
                            )