How change connection string dynamically in c#`

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Hi
I am doing windows project on that i have a requirement that the connection string has change dynamically means when ever user upload a excel file on that time the connection string should be the uploaded file`s connection string

C#

private void txtExtractFile_TextChanged(object sender, EventArgs e)
{
     Compare();
}
 
public void Compare()
{ 
OleDbConnection con; // create connection
OleDbDataAdapter da;
con = new OleDbConnection("Provider = Microsoft.Jet.OLEDB.4.0; Data Source = D:\\Projects\\WIP\\Database.mdb");
// open the coinnection
con.Open();
DataTable dt = new DataTable();
da = new OleDbDataAdapter("SELECT * FROM Sysobjects where TABLE_TYPE=TABLE", con);
dt = con.GetSchema("tables");
int found = 0;
string s1 = "Emp";
string s2 = "Student";
string s3 = "Projects";
 

for (int i = 0; i < dt.Rows.Count; i++)
{
 
//if (dt.Rows[i][2].ToString().Contains("Emp") || dt.Rows[i][2].ToString().Contains("Student") || dt.Rows[i][2].ToString().Contains("Projects"))
//{
// found++;
 
//}
//
if (s1 == dt.Rows[i][2].ToString()
|| s2 == dt.Rows[i][2].ToString()
|| s3 == dt.Rows[i][2].ToString())
{
found++;
}
}
if (found == 3)
{
MessageBox.Show("hi");
}
//bool bfound = false;
//string s1 = "emp";
//for (int i = 0; i < dt.Rows.Count; i++)
//{
// s1 = dt.Rows[i][2].ToString();
// bFound = true;
 
//}
con.Close(); //Close the connection 
}

Posted 20-May-12 19:41pm

MAKReddy

Updated 20-May-12 20:19pm

JF2015

v2

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Comments

Maciej Los 21-May-12 2:08am

Where is a problem? What have you done so far?

MAKReddy 21-May-12 2:17am

Hi Losmac i copeied code see the database path D:\\Projects\\WIP\\Database.mdb");

but this path will be change every time at that time i want to change in code behind also. how it will change dynamically this path.

Dholakiya Ankit 16-Jul-13 0:50am

solutions 4 is right

CHill60 16-Jul-13 13:47pm

And yet Solution 2 has the most votes!

5 solutions

Solution 5

since the dataset connection string is read only you must use the code below to be able to modify its default read only connection string :)

C#

Console.WriteLine(Properties.Settings.Default["DataSetCS"]);
Properties.Settings.Default["DataSetCS"] = yourNewConnectionString;
Console.WriteLine(Properties.Settings.Default["DataSetCS"]);

Posted 15-Jul-13 16:26pm

marcoshepperson

Updated 15-Jul-13 16:28pm

v2

Solution 3

you can store your connection string in app.config and use this code to change the value of connection strinh

C#

ConfigurationManager.ConnectionStrings["student"].ConnectionString = "val";

Posted 21-May-12 1:52am

hunain.esh

Solution 4

Hellow, just create a separate win form app where u put options like
dbname

server name
uid (if available)
password (if availabe)

and a connect button.
on connect button just open and close the connection, if its get connected then save it to a file like each value in different line.
i.e.
mySqlServer
myDbName
myUid
myPass
and each time when u open or run ur project read the file line by line. \
Thats it ur done with dynamic connection string.

Posted 21-May-12 2:33am

vishal_jaimataji

Solution 6

The simple way is to store connection string in the database. Create a table in your database. On each successfull data file upload, enter an entry in this table with appropriate connection string.

You only need to read that table to read the connection string. This should get you going.

Posted 15-Jul-13 18:47pm

_Asif_

Comments

tedebus 21-Feb-14 9:22am

Is it a joke?
How can you connect to database without connection string?! It's a loop!

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Prasad_Kulkarni · Accepted Answer · 2012-05-20T20:26:00

Configuration is read only so you can not do it in obvious way like;

C#

ConfigurationManager.ConnectionStrings["student"].ConnectionString = "new value";

This raises System.Configuration.ConfigurationErrorsException[^] exception which saying that "Configuration is read only".

Here is a trick using reflection to reset readOnly attribute of configuration element. See this article for full details Programmatically setting a connectionString property[^]

C#

var settings = ConfigurationManager.ConnectionStrings[ 0 ];
var fi = typeof(ConfigurationElement).GetField(
              "_bReadOnly", 
              BindingFlags.Instance | BindingFlags.NonPublic);
fi.SetValue(settings, false);
settings.ConnectionString = "Data Source=Something";

Also refer:
How to dynamically change connection string in generated dataset class? [^]
Dynamically change connectionString in web.config[^]