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C # DataTable Internal join with dynamic columns

I am trying to combine two DataTables along with this question:

Internal DataTables join in C #

I am trying to get the output as a single "combined" table with columns from both source tables. They will both have a datestamp column.

The above answer is good for DataTables with fixed columns, but what if they are created dynamically and can have any number of columns, how can I join them?

eg.

T1 (datestamp, t1Column1, t1Column2, t1ColumnN...)
T2 (datestamp, t2Column1, t2Column2, t2ColumnN...)

I would like to join in to create the following:

J1 (datestamp, t1Column1, t1Column2, t1ColumnN, ..., t2Column1, t2Column2, t2ColumnN...)

Is it possible?

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3 answers

I found a solution that does not rely on a loop through columns.

"", , , .

:

// set primary key
T1.PrimaryKey = new DataColumn[] { T1.Columns["DateStamp"] };
T2.PrimaryKey = new DataColumn[] { T2.Columns["DateStamp"] };

, :

// add both data-tables to data-set
DataSet dsContainer = new DataSet();
dsContainer.Tables.Add(T1);
dsContainer.Tables.Add(T2);

:

// add a relationship between the two timestamp columns
DataRelation relDateStamp = new DataRelation("Date", new DataColumn[] { T1.Columns["DateStamp"] }, new DataColumn[] { T2.Columns["DateStamp"] });
dsContainer.Relations.Add(relDateStamp);

, "" , :

// populate combined data
DataTable dtCombined = new DataTable();
dtCombined = T1.Copy();
dtCombined.Merge(T2, false, MissingSchemaAction.Add);

. Merge , , .

:

T1 (2012-05-09, 111, 222)
T2 (2012-05-09, 333, 444, 555)

:

J1 (2012-05-09, 111, 222, 333, 444, 555)
+7

, , , . , :

foreach(DataRow row in table.Rows)
{
    foreach(DataColumn column in table.Columns)
    {
        object value = row[column]; // add this to your combined table
    }
}
+1

After you get tired of seeing all of these internal join functions that unreliably emulate SQL, I decided to make my own here:

private DataTable JoinDataTables(DataTable t1, DataTable t2, params Func<DataRow, DataRow, bool>[] joinOn)
{
    DataTable result = new DataTable();
    foreach (DataColumn col in t1.Columns)
    {
        if (result.Columns[col.ColumnName] == null)
            result.Columns.Add(col.ColumnName, col.DataType);
    }
    foreach (DataColumn col in t2.Columns)
    {
        if (result.Columns[col.ColumnName] == null)
            result.Columns.Add(col.ColumnName, col.DataType);
    }
    foreach (DataRow row1 in t1.Rows)
    {
        var joinRows = t2.AsEnumerable().Where(row2 =>
            {
                foreach (var parameter in joinOn)
                {
                    if (!parameter(row1, row2)) return false;
                }
                return true;
            });
        foreach (DataRow fromRow in joinRows)
        {
            DataRow insertRow = result.NewRow();
            foreach (DataColumn col1 in t1.Columns)
            {
                insertRow[col1.ColumnName] = row1[col1.ColumnName];
            }
            foreach (DataColumn col2 in t2.Columns)
            {
                insertRow[col2.ColumnName] = fromRow[col2.ColumnName];
            }
            result.Rows.Add(insertRow);
        }
    }
    return result;
}

An example of how you can use this:

var test = JoinDataTables(transactionInfo, transactionItems,
               (row1, row2) =>
               row1.Field<int>("TransactionID") == row2.Field<int>("TransactionID"));
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