using System;
	using System.Collections.Generic;
	using System.ComponentModel;
	using System.Data;
	using System.Drawing;
	using System.Linq;
	using System.Text;
	using System.Windows.Forms;
	using System.Data.SqlClient;
	
	namespace MySqlTest
	{
		public partial class Form1 : Form
		{
			SqlConnection myDB = new SqlConnection(@"Data Source=MEDESKTOP;AttachDbFilename=|DataDirectory|\SqlTestDB.mdf;Initial Catalog=MySqlDB;Integrated Security=True");
			SqlDataAdapter myDA = new SqlDataAdapter();
			SqlCommand mySqlCmd = new SqlCommand();
	
			string mySQLcmd;
			int myCount;
	
			public Form1()
			{
				InitializeComponent();
			}

			private void button1_Click(object sender, EventArgs e)
			{
				MessageBox.Show("myDB state = " + myDB.State.ToString());
				//Open SQL File
				myDB.Open();
				MessageBox.Show("myDB state = " + myDB.State.ToString());
			}
	
			private void button2_Click(object sender, EventArgs e)
			{
				myCount++;
				MessageBox.Show("myCount = " + myCount.ToString());
				//Insert Record Into  SQL File
				mySqlCmd.Connection = myDB;
				mySqlCmd.CommandText = "INSERT INTO Parent(ParentName) Values(myCount)";
				myDA = new SqlDataAdapter(mySqlCmd);
				mySqlCmd.ExecuteNonQuery();
			}
	
			private void button3_Click(object sender, EventArgs e)
			{
				//Read Record From SQL File
	
			}
	
			private void button4_Click(object sender, EventArgs e)
			{
				//Read All Records From SQL File
	
			}
	
			private void button5_Click(object sender, EventArgs e)
			{
				//Delete Record From DQL File
			}
	
			private void button6_Click(object sender, EventArgs e)
			{
				MessageBox.Show("myDB state = " + myDB.State.ToString());
				//Close SQL File
				myDB.Close();
				MessageBox.Show("myDB state = " + myDB.State.ToString());
			}
	
			private void button7_Click(object sender, EventArgs e)
			{
				//Quit
				this.Close();
			}
		}
	}

SELECT user_access_desc FROM sys.databases WHERE [name] = 'MyDatabaseName'

quote:

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Originally posted by Kristen

Is your database set to SINGLE USER mode perhaps?

SELECT user_access_desc FROM sys.databases WHERE [name] = 'MyDatabaseName'

or you are not closing a connection, or not retrieving all the data from a dataset before attempting to reuse the connection.

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quote:

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Originally posted by sunitabeck

The connection string you are using is useful if you want to read data directly from an MDF file that is NOT ATTACHED TO A SERVER. If you have an instance of SQL Server installed on your computer, and if you are able to see this database from the SQL Server Management Studio's object explorer, then the database is attached to the server. If that is true, use a different connection string that indicates the server name etc. Typical connection strings used are available here: http://connectionstrings.com/sql-server-2008

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