constraintexception

问题 Just as a starting note: I'm going through an existing app which was passed down to us and trying to go through and fix the bugs. I've been having issues with one particular DataGridView erroring out; giving me a Unique Constraint Exception on the ID. The strange thing is that I don't receive this error when I add the new item to the table, I receive it when I try to select a row (any row, it doesn't have to be the newly added item) in the DataGridView. When you add an item to this table it

问题 so I have quite the odd predicament here. My SQL table is set to allow nulls for my ZipCode column, like so: CREATE TABLE [dbo].[Companies] ( [CompanyId] BIGINT IDENTITY(1,1) NOT NULL PRIMARY KEY, [Name] NVARCHAR(100) NOT NULL, [Address] NVARCHAR (100) NULL, [City] NVARCHAR (50) NOT NULL, [State] NVARCHAR (2) NOT NULL, [ZipCode] INT NULL, [PhoneNum] BIGINT NULL, [CreatedDate] DATETIME2 NOT NULL DEFAULT GetDate() ) This should let me have ZipCode's value as NULL, right? Well, apparently not...