如何在Gridview上合并/加入两个不同的数据源？

Question

I have two databases and tables. I need to join two tables on one datasource for Gridview. (I can't use DBLINK)

try
{
OleDbConnection Connection1;
    using (Connection1 = new OleDbConnection("Provider=MSDAORA.1;Data Source=DATABASE1:1521/orcl;Persist Security Info=True;Password=PASSWORD;User ID=USERNAME;"))
    {
        string sqlQuery = "select * from DB1_TABLE";

        using (OleDbDataAdapter cmd = new OleDbDataAdapter(sqlQuery, Connection1))
        {
                Connection1.Open();
                DataTable dt = new DataTable();
                cmd.Fill(dt);
                GridView1.DataSource = dt;
                GridView1.DataBind();
                Connection1.Close();
        }
    }
}
catch (Exception)
{
}


try
{
OleDbConnection Connection2;
    using (Connection2 = new OleDbConnection("Provider=MSDAORA.1;Data Source=DATABASE2:1521/orcl;Persist Security Info=True;Password=PASSWORD;User ID=USERNAME;"))
    {
        string sqlQuery = "select * from DB2_TABLE";

        using (OleDbDataAdapter cmd = new OleDbDataAdapter(sqlQuery, Connection2))
        {
                Connection2.Open();
                DataTable dt = new DataTable();
                cmd.Fill(dt);
                GridView1.DataSource = dt;
                GridView1.DataBind();
                Connection2.Close();
        }
    }
}
catch (Exception)
{
}

Like this:

And sometimes db1 or db2 getting error. I need to see other db values if getting one of them error like this:

or

How can I do this? Could you show me some example on my sample code? Thank you.

-

I tried dataset.merge like this:

    dt1.Merge(dt2, true, MissingSchemaAction.Add);
    GridView1.DataSource = dt1;
    GridView1.DataBind();

But getting output like this:

How can I fix that?

Answer 1

Something along these lines:

        var data1 = new List<Data1>
        {
            new Data1 { Name = "A", Date1 = DateTime.Now },
            new Data1 { Name = "B", Date1 = DateTime.Now }
        };

        var data2 = new List<Data2>
        {
            new Data2 { Name = "C", Date3 = DateTime.Now },
            new Data2 { Name = "D", Date3 = DateTime.Now },
        };


        var query = from key in data1.Select(item => item.Name)
                        .Union(data2.Select(item => item.Name))

        join datum1 in data1 on key equals datum1.Name into kd1
        from sub1 in kd1.DefaultIfEmpty()

        join datum2 in data2 on key equals datum2.Name into kd2
        from sub2 in kd2.DefaultIfEmpty()

        select new
        {
            Name = key,
            Date1 = sub1?.Date1,
            Date2 = sub1?.Date2,
            Date3 = sub2?.Date3,
            Date4 = sub2?.Date4
        };

I'm first creating a list of all the Names that you have recieved and then left joining each data source to that names list.

Answer 2

You can do it as follow :

• retrieve the first query result which is form certain DB in dataset1

• retrieve the first query result which is form certain DB in dataset2

• use DataSet.Merge Method to merge the two data set in say datasetMaster

• bind datasetMaster to the grid

Update :

Also a easiest way around this would be a SP where you have a linked database server between DB1 and DB2 and you can then reference that table from DB1 in DB2 .

So it will have some code like:

SELECT d.ColA, d.ColB, d.ColC
FROM dbo.MyTable d
UNION ALL
SELECT b.ColA, b.ColB,b.ColC
FROM DB1.dbo.MyOtherTable b

More Info Linked Servers