主键列已设置默认标识(1, 1)时如何向sql server数据库插入数据

Question

I'm trying to insert two data columns into my SQL Server database but I get an error at the code line -> cmd.ExecuteNonQuery();

Cannot insert the value NULL into column OrderID , table RestaurantApp.dbo.Junc_Order ; column does not allow nulls. INSERT fails.

The OrderID column is actually the primary key in my data table. I set it identity(1, 1) and want to insert other data and meanwhile it can insert 1, 2, 3, 4....automatically.

Here is the part of my code:

string insertString = "INSERT INTO Junc_Order(ID, Quantity)values (@ID, @Quantity)";
SqlCommand cmd = new SqlCommand(insertString, conn);
cmd.Parameters.AddWithValue("@ID", r_ID);
cmd.Parameters.AddWithValue("@Quantity", r_Quantity);
cmd.ExecuteNonQuery();

I already get connection with database ahead of these codes, so the problem should not be that.

Updated Junc_Order table design:

OrderID (PK,FK,int,not null)

ID(FK,int,not null)

Quantity(int,not null)

Answer 1

By viewing your question, it seems that your insert query is not correct:

1. First of all, you don't need to insert "OrderID" as it is primary key identity so sql server automatically insert it.

2. second, somewhere you are getting "r_ID" as null that's why you are facing error.Verify it and modify your code with the following:

   string insertString = "INSERT INTO Junc_Order(Quantity) values(@Quantity)"; SqlCommand cmd = new SqlCommand(insertString, conn); cmd.Parameters.AddWithValue("@Quantity", r_Quantity); cmd.ExecuteNonQuery();