how to write like operation of sql use in C# by linq

diamond diamond

Hi

Is there possible to write such a sql query by linc in C#?

I have two tables (kv2, kv2dns), I want to select destination feild from kv2dns which has some common condition with kv2 table

if (dt.dport=53) dt is datatable for kv2 table has

{

list hosts = Select destination_address from kv2dns where kv2.saddr=kv2dns.destination_address and kv2.daddr=kv2dns.source and kv2dns.info like ' no such name' ;

}

7 Replies

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Jignesh Trivedi13y ago
Accepted answer
hi,
If both kv2 and kv2dns are data table then
var kv2 = ds.Tables["kv2"].AsEnumerable();
var kv2dns = ds.Tables["kv2dns"].AsEnumerable();
var query =
    from a in kv2
    join b in kv2dns on a.Field("source")
    equals b.Field("destination_address")
    where b.Field("info").Contains("name")
    select new
    {
        DA = b.destination_address
    };
hope this will help you.
diamond diamond13y ago
Any idea?
diamond diamond13y ago
dt has some fields such as src, dst, time, dport
kv2dns has some fields such as source, destination, info

src and destination values are the same.
dst and source values are the same.
but no tables have primary key
diamond diamond13y ago
Hi,

I have 2 table kv2 and kv2dns, which kv2 has a data table is named dt but kv2dns has not.
I want if dt.dport field be 53, hen compare dt with kv2dns for knowing that is there any dt.src=kv2dns.dst and kv2dns. info has 'no such name', if ok the kv2dns.dst is put in a list
Jignesh Trivedi13y ago
hi,

not sure why you are write such complicated query.
can please me details like
1) are you use datatable or dataset to retrieve the data?
2)provide relationship between table

here you are writting from clause just before where....
actually syntex of Linq is wrong.
without knowing relation i am not able to write query.
diamond diamond13y ago
Thanks Jegnesh,

When I wrote such as below, gives an error.

var q = from k in dcdns.kv2dns where
from DataRow dr in dt.Rows where (dr["saddr"] == dcdns.kv2dns.Select (s=>s._Destination_) && dr["daddr"] == dcdns.kv2dns.Select (s =>s._Source_ ) && dcdns.kv2dns.Select (s=>s._Info_ .Contains("no such name")) )
select new { k._Destination_ } ;

Error:A query body must end with a select clause or a group clause
Jignesh Trivedi13y ago
hi,
using "Contains" key word you can achieve functionality same as like key word in SQL.
example.
var host = from kv2 in kv2dns
where v2.saddr equals kv2dns.destination_address && kv2.daddr equals kv2dns.source && kv2dns.info.Contains("no such name")
select { destination_address }

hope this will help you.