Dynamic where clause for joined System.Data.DataTable in Linq C# - linq

Question

I'd like to create a dynamic where clause for variable amount of columns. Can this be done?
I think I've looked at all the posts related to this topic but still cannot find the answer.
var results = from table1 in dt1.AsEnumerable()
join table2 in dt2.AsEnumerable() on table1.Field<int>("ID") equals table2.Field<int>("ID")
where table1["ColumnA"].ToString() != table2["ColumnA"].ToString() ||
table1["ColumnB"].ToString() != table2["ColumnB"].ToString() ||
table1["ColumnC"].ToString() != table2["ColumnC"].ToString()
select table1;

Answer 1

You can logically add where clauses. Here's an extension method that does it
(it's not mine, I saw it somewhere here on StackOverflow, a long time ago. I'll reference it when I find it)
Func<T, bool> And(this Func<T, bool> a, Func<T, bool> b)
{
return (T x) => a(x) && b(x);
}
With it, you can iterate over the columns and add them to the where clause:
Func<string, bool> whereClause = x => true;
foreach(string columnName in dt.Columns.Select(x => x.ColumnName)
{
string first = dt.Columns[columnName].ToString();
string second = dt2.Columns[columnName].ToString();
whereClause = whereClause.And(x => first.Equals(second));
}
var result = (from foo in bar select fooBar).Where(whereClause);

Answer 2

You could use either System.Linq.Dynamic(ScottGu's blog article and nuget) in case of dynamic where clause:
var results = (from fruit in fruits
join car in cars on fruit.Id equals car.Id
select new { fruit, car })
.AsQueryable()
.Where("fruit.ColA != car.ColA")
.Where("fruit.ColB == car.ColB");
Or dynamicaly build expressions this using extensions from PredicateBuilder writen by #joe-albahari. For example:
var predicate =
PredicateBuilder
.True<Tuple<Product, Product>>()
.And(t => t.Item1.ColA != t.Item2.ColA)
.And(t => t.Item1.ColB == t.Item2.ColB)
.Compile();
(from fruit in fruits
join car in cars on fruit.Id equals car.Id
select Tuple.Create(fruit, car))
.Where(predicate)
.Dump();
ps: full code available at gisthub