無法從代碼

Question

連接到SQL Server數據庫中，我曾嘗試與下面的代碼：

private void button2_Click(object sender, EventArgs e) 
{ 
    string connString = @"Server=localhost;Initial Catalog=Database2;User id=***;Password=***;"; 

    SqlConnection sqlConn = new SqlConnection(connString); 

    string sqlQuery = @"SELECT * from tableP"; 
    SqlCommand cmd = new SqlCommand(sqlQuery, sqlConn); 

    SqlDataAdapter da = new SqlDataAdapter(cmd); 
    DataTable table = new DataTable(); 
    da.Fill(table); 

    DataGridView dgv = new DataGridView(); 
    dgv.DataSource = new BindingSource(table, null); 
} 

其他信息：

A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)

Answer 1

您需要先對數據庫進行任何操作前打開連接。

sqlConn.Open(); 

和與此相關的字符串

connectionString="Data Source=localhost;Initial Catalog=Database2; User ID=myUsername;Password=myPassword;" 

Answer 2

試試這個

private void button2_Click(object sender, EventArgs e) 
{ 
     string connString = 'yourconnectionstring' 
     SqlConnection sqlConn = new SqlConnection(connString); 
    try 
    { 

     sqlConn.Open(); 
     string sqlQuery = @"SELECT * from tableP"; 
     SqlCommand cmd = new SqlCommand(sqlQuery, sqlConn); 
     SqlDataAdapter da = new SqlDataAdapter(cmd); 
     DataTable table = new DataTable(); 
     da.Fill(table); 
     DataGridView dgv = new DataGridView(); 
     dgv.DataSource = new BindingSource(table, null); 
    } 
    catch (Exception) 
    { 

     SqlConn.Close(); 
    } 
    finally 
    { 
     SqlConn.Close(); 
    } 
}