SelectedIndex没有插入正确的值

Question

I have a method to insert user information into the SQL Server database. I have my combobox populate on pageload event. The user selects the input they want and hit update if they are updating a old record or insert if creating a new record. When they do so my database is not storing the right value if they select 4 it stores 3. Here is my insert method and populate method.

Insert method: I have to join the StockID because it is a primary key.

using (dbConn2 = new SqlConnection(Properties.Settings.Default["tville"].ToString()))
{
   SqlCommand addNewFormat = new SqlCommand(@"INSERT INTO PackLabelFormat ( PackFormatID, Description, PrintWeight, PrintPlantCode, PrintPrice, StockID) VALUES (@PackFormatID, @Description, @PrintWeight, @PrintPlantCode, @PrintPrice, (SELECT @StockID from LabelStockReference LSR WHERE LSR.StockID = @StockID))", dbConn2);

   addNewFormat.Parameters.AddWithValue("@PackFormatID", Convert.ToInt32(IDselect));
   addNewFormat.Parameters.AddWithValue("@Description", rTxtBoxDescription.Text);
   addNewFormat.Parameters.AddWithValue("@PrintPrice", rChkBoxPrintPrice.Checked);
   addNewFormat.Parameters.AddWithValue("@PrintWeight", rChkBoxWeight.Checked);
   addNewFormat.Parameters.AddWithValue("@PrintPlantCode", rChkBoxPlantCode.Checked);
   addNewFormat.Parameters.AddWithValue("@StockID", Convert.ToInt32(cmboBoxStock.SelectedIndex));

   dbConn2.Open();
   addNewFormat.ExecuteNonQuery();

Populate method:

if (labelList != null)
{
   foreach (LabelData l in labelList)
   {
       cmboBoxStock.Items.Add(string.Format("{0} - {1}", l.PackFormatID, l.Description));
   }
}

If there is anything else I'm leaving out just let me know. Thanks.

Answer 1

There are two options for your INSERT statement:

(1) you can use INSERT ... VALUES .... and in this case, you must supply as many values as you have columns to insert data into, and you have to supply literal values or SQL Server variables only - you cannot use a SELECT to provide a value:

 DECLARE @ASqlServerVariable VARCHAR(100)
 SET @ASqlServerVariable = 'any possible value that's legal for this datatype'

 INSERT INTO dbo.YourTable(ID, Col1, Col2, Col3) 
 VALUES (42, 'Some fixed value', @ASqlServerVariable, 'Another literal value')

What you could do is use a SELECT to store the value you're interested in into a SQL Server variable:

DECLARe @StockID INT

SELECT @StockID = ID 
FROM dbo.LabelStockReference LSR 
WHERE LSR.StockID = 4711

(2) if you can't provide all literal values or variables, then you must use the INSERT .... SELECT ... option, which requires you to provide as many columns in your SELECT as the INSERT expects to insert a row into the target table:

 DECLARE @ASqlServerVariable VARCHAR(100)
 SET @ASqlServerVariable = 'any possible value that's legal for this datatype'

 INSERT INTO dbo.YourTable(ID, Col1, Col2, Col3) 
    SELECT 
        42, 'Some fixed value', @ASqlServerVariable, aTableColumn
    FROM
        dbo.SomeOtherTable

See the official TechNet documentation for INSERT for all the details and exact syntax of all possible options etc.

Answer 2

第一个SelectedIndex为0，而您的第一个ID为1，所以只需进行以下更改：

addNewFormat.Parameters.AddWithValue("@StockID", Convert.ToInt32(cmboBoxStock.SelectedIndex)+1);