从C＃将整数值插入SQL Server数据库

Question

I am trying to insert an integer value into a SQL Server database as below when I run the program there are no any errors, but the table doesn't get updated with values. I have searched on the internet and I am doing the same can anyone help to find what I am doing wrong.

Note: I already defined "connectionString" as a string on the form class

private void btnUpdate_Click(object sender, EventArgs e)
{
        int totalincome=600;
        int totaldeductions = 10;

        connectionString = ConfigurationManager.ConnectionStrings["BudgetApp.Properties.Settings.MainDataBaseConnectionString"].ConnectionString;

        con = new SqlConnection(connectionString);

        con.Open();

        cmd = new SqlCommand("INSERT INTO Totals(TotalIncome, TotalDeductions) VALUES (@TotalIncome, @TotalDeductions)", con);
        cmd.Parameters.AddWithValue("@TotalIncome", totalincome);
        cmd.Parameters.AddWithValue("@TotalDeductions", totaldeductions);

        cmd.ExecuteNonQuery();

        MessageBox.Show("Done !!");
}

Answer 1

The whole AttachDbFileName= approach is flawed - at best! When running your app in Visual Studio, it will be copying around the .mdf file (from your App_Data directory to the output directory - typically .\\bin\\debug - where you app runs) and most likely , your INSERT works just fine - but you're just looking at the wrong .mdf file in the end!

If you want to stick with this approach, then try putting a breakpoint on the myConnection.Close() call - and then inspect the .mdf file with SQL Server Mgmt Studio Express - I'm almost certain your data is there.

The real solution in my opinion would be to

1. install SQL Server Express (and you've already done that anyway)

2. install SQL Server Management Studio Express

3. create your database in SSMS Express , give it a logical name (eg MainDataBase )

4. connect to it using its logical database name (given when you create it on the server) - and don't mess around with physical database files and user instances. In that case, your connection string would be something like:

    Data Source=.\\\\SQLEXPRESS;Database=MainDataBase;Integrated Security=True 

   and everything else is exactly the same as before...

Also see Aaron Bertrand's excellent blog post Bad habits to kick: using AttachDbFileName for more background info.

Answer 2

Code Seems correct,Perhaps you are checking the wrong DB?. I would add a Try/catch for exceptions. And remember to close connection after executing query. Regards

Answer 3

check your database column datatype,use try catch.

and try to replace cmd.Parameters.AddWithValue("@TotalIncome", totalincome); to cmd.Parameters.Add("@Number", SqlDbType.Int).Value = totalincome;

try
{
       int totalincome=600;
        int totaldeductions = 10;
        connectionString = ConfigurationManager.ConnectionStrings["BudgetApp.Properties.Settings.MainDataBaseConnectionString"].ConnectionString;
        con = new SqlConnection(connectionString);
        con.Open();
        cmd = new SqlCommand(@"INSERT INTO Totals(TotalIncome, TotalDeductions) VALUES (@TotalIncome, @TotalDeductions)", con);

        cmd.Parameters.Add("@Number", SqlDbType.Int).Value = totalincome;
        cmd.Parameters.Add("@Number", SqlDbType.Int).Value = totaldeductions;
        //cmd.Parameters.AddWithValue("@TotalIncome", totalincome);
        //cmd.Parameters.AddWithValue("@TotalDeductions", totaldeductions);

        cmd.ExecuteNonQuery();
}
catch(Exception ex)
{
  MessageBox.Show(ex.ToString());
}