How to merge two datatables and remove duplicate rows

I have two datatables with identical columns, the uniqueness is based on three columns
ID, Code and BusDate

How can I remove the duplicates
dt1.Merge(dt2) does not remove the duplicates because there are a total of six columns
LVL 1
countrymeisterAsked:
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AndyAinscowFreelance programmer / ConsultantCommented:
Use an append query.

1.

Append all the rows in one table

2.

Now append all the rows in the second where there is NO match in those three columns (x != x1 and y != y1 and z != z1)
0
AndyAinscowFreelance programmer / ConsultantCommented:
oops, use an OR not the and in the condition

Use an append query.
Append all the rows in one table
Now append all the rows in the second where there is NO match in those three columns (x != x1 or y != y1 or z != z1)
0
apeterCommented:
Hope this helps.

var distinctItems = <yourDatamodelCollection>.Distinct();

To match on only some of the properties, create a custom equality comparer, e.g.:

class DistinctItemComparer : IEqualityComparer<Item> {

    public bool Equals(Item x, Item y) {
        return x.Id == y.Id &&
            x.Name == y.Name &&
            x.Code == y.Code &&
            x.Price == y.Price;
    }

    public int GetHashCode(Item obj) {
        return obj.Id.GetHashCode() ^
            obj.Name.GetHashCode() ^
            obj.Code.GetHashCode() ^
            obj.Price.GetHashCode();
    }
}
Then use it like this:

var distinctItems = <yourDatamodelCollection>.Distinct(new DistinctItemComparer());
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louisfrCommented:
Set the PrimaryKey property of the DataTable objects. You can do that in the designer if you have a typed dataset, or do it in code:
dt1.PrimaryKey = new[] { dt1.Columns["ID"], dt1.Columns["Code"], dt1.Columns["BusDate"] };
dt2.PrimaryKey = new[] { dt2.Columns["ID"], dt2.Columns["Code"], dt2.Columns["BusDate"] };

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You can then have dt2 rows overwrite rows from dt1 with the same keys:
dt1.Merge(dt2);

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or have dt1 rows preserved:
dt1.Merge(dt2, true);

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