Select values from diferent db with same app C#

Goran Bibic

I have some simple app

Two database:
1) 2017 (table name partners(id, name))
2) 2018 (table name partners(id, name))

On Form 1 have username, password, button login and combo box.
On Form 2 empty partnerdatagrid

I need when in combobox chose value 2017 show data from database 2017 (table name partners(id, name)),
if choose value 2018 to show data from 2018 (table name partners(id, name))

Some help?

Combobox value are find on next way

InitializeComponent();
comboBox1.DataSource = GetDatabaseList();

public List<string> GetDatabaseList()
{
List<string> list = new List<string>();
using (SqlConnection con = new SqlConnection(cs))
{
con.Open();
// Set up a command with the given query and associate
// this with the current connection.
using (SqlCommand cmd = new SqlCommand("SELECT name from sys.databases where name like '20%'", con))
{
using (IDataReader dr = cmd.ExecuteReader())
{
while (dr.Read())
{
list.Add(dr[0].ToString());
}
}
}
}
return list;
}

4 Replies

Know the answer? Post it — somebody with the same question will find it here.

Suraj Kumar8y ago
Accepted answer
Hello Goran,

You can create a method or function with with parameter string and then pass the value of combobox as parameter of that method as below.

Based on the value of pamater you can write a dynamic sqlconnection. Create and Call the below method on selected value changed event of combobox.

// your method to pull data from database to datatable

public void PullData(string databaseName)

{

string connString= "";

if (databaseName == "2017")

{

SqlConnection connString= new SqlConnection ("DataSource=...; Initial Catalog=2017;User Id=...; Password=...");

}else if (databaseName == "2018")

{

SqlConnection connString= new SqlConnection ("DataSource=...; Initial Catalog=2018;User Id=...; Password=...");

}

string query = "select * from partners";

SqlCommand cmd = new SqlCommand(query, conn);

conn.Open();

// create data adapter

SqlDataAdapter da = new SqlDataAdapter(cmd);

// this will query your database and return the result to your datatable

da.Fill(dataTable);

conn.Close();

da.Dispose();

}

Thanks

Suraj
Goran Bibic8y ago
Yes. Just use that value from combobox on Form1. Thank you so much. Thank you
Goran Bibic8y ago
Some recommendation?

I have same tables in two database. One year one database.

I need when login in app to choose conn string 2017 to show data from database 2017, when chose conn string 2018 to show data from database 2018.

Choose from combobox (2017,2018).

Some help?
Tapan Patel8y ago
Not sure about the designing the code that way but if you need to switch the database, inverse the connection dependency from GetDatabaseList.

Meaning modify your method to accept the parameter of type SqlConnection.
That way, calling method would have to provide the right connection object.