Question

I am trying to compare two tables (i.e values, count, etc..) in linq to sql but I am not getting the way to achieve it. I tried the following,

Table1.Any(i => i.itemNo == Table2.itemNo)

It gives error. Could you please help me?

Thanks in Advance.

Answer 1

how about

var isDifferent =
        Table1.Zip(Table2, (j, k) => j.itemNo == k.itemMo).Any(m => !m);

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EDIT

if Linq-To-Sql does not support Zip.

var one = Table1.ToList();
var two = Table2.ToList();

var isDifferent =
        one.Zip(two, (j, k) => j.itemNo == k.itemMo).Any(m => !m);

if the tables are vary large this could cause performance problems. In that case you will need a much more sophisticated solution, if so, please ask.

EDIT2

If the tables are very large you don’t want to get all the data from the server and hold it memory. Additionaly, Linq and SQL server do not garauntee the order of the rows unless you specify an order in the query. This becomes espcially relavent for large result sets returned by a multi processor server where the effects of parallelism are likely to come into play.

I suggest that Linq-to-Sql doesen’t really cater well for your scenario so you will have to help it out using ExecuteQuery somthing like this.

string zipQuery =
@"SELECT TOP 1
        1
    FROM
        [Table1] [one]
    WHERE
        NOT EXISTS (
           SELECT * FROM [Table2] [two] WHERE [two].[itemNo] = [one].[itemNo]
        )
UNION ALL
SELECT
        1
    FROM
        [Table2] [two]
    WHERE
        NOT EXISTS (
           SELECT * FROM [Table1] [one] WHERE [one].[itemNo] = [two].[itemNo]
        )
UNION ALL
SELECT 0";

var isDifferent = context.ExecuteQuery<int>(zipQuery).Single() == 1; 

This will do the select on the server without returning lots of data to the client but, I think you will agree is much more complicated.

---

EDIT3

Okay, the zip approach should be fine for 1000 rows. I’ve read your comment and I suggest changing the code accordingly.

var one = Table1.ToList();
var two = Table2.ToList();

var isDifferent =
    one.Count != two.Count ||
    one.Zip(two, (o, t) => o.itemNo == k.itemNo).Any(m => !m);

You should probably consider putting an order by on the list retrievers, like this.

var one = Table1.OrderBy(o => o.itemNo).ToList();

Strictly, the results of a Linq-to-Sql come back in any order unless an order is specified.