在SQL Server中连接两个数据库

Question

private void button1_Click(object sender, EventArgs e)
{
        SqlConnection con = new SqlConnection();
        con.ConnectionString = "Data Source= shwn-PC\\SQLEXPRESS;Initial Catalog=database1;Integrated Security=True";

        con.Open();

        SqlCommand cmd = new SqlCommand("select * from table1 where A ='" + textBox1.Text.Trim() + "'", con);

        SqlDataReader dr = cmd.ExecuteReader();

        if (dr.HasRows)
        {
            while (dr.Read())
            {
                textBox2.Text = dr["A"].ToString();
                textBox3.Text = dr["B"].ToString();
            }
        }
        else
            MessageBox.Show("No record  >> " + textBox1.Text.ToString());
    }
}

How can I connect two databases and show a certain column combined with another column from the other database?

Like in the textbox3 I want to show the B value from this database plus C value from database2, table2

Answer 1

If both databases exist in one single server, you can use database name as prefix for table name:

SELECT a.col1, b.col2 FROM db1.TableA a
INNER JOIN db2.TableB b ON b.Id = a.LinkId

Reference

Answer 2

SELECT *  FROM [DB1].[dbo].[Table1],[DB2].[dbo].[Table2]

Try to use something like above. This is just a sample, I have use this to join two table from two different database.