auto number ID column in datagridview from sql column and become auto count after delete any rows c#?

Question

• hello all , i wanna create Table in sql Server (Ex: employe) this table have columns (ID, FName, LName, age ..etc

  • i need ID column add auto number for each new row automatic. i Set the Identity specification to yes like this : Identity specification

but if did this setting in ID column i will face another issue like this picture : open this picture

• now how to make ID column become auto count after delete any rows?

so i thought i should make a loop to add new number in ID value every new record . and count the ID column every deleting row to reset the list of number in ID column .

i think my idea is clear now . so any help in this to make it work . i'm using c# .

Answer 1

Lets say you have an employee table definition:

CREATE TABLE [dbo].[Employee](
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [FirstName] [varchar](50) NULL,
    [LastName] [varchar](50) NULL,
    [DateOfBirth] [datetime] NULL,
    [SequenceNumber] [int] NOT NULL,
    [DateTimeStamp] [datetime] NOT NULL,
 CONSTRAINT [PK_Employee] PRIMARY KEY CLUSTERED 
(
    [Id] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

SET ANSI_PADDING OFF
GO

ALTER TABLE [dbo].[Employee] ADD  CONSTRAINT [DF_Employee_DateTimeStamp]  DEFAULT (getdate()) FOR [DateTimeStamp]
GO

The ID is set to primary key and auto increment. The SequenceNumber column is the one we are interested in. It will be kept in sequence as your requirements are. DateTimeStamp is also set to current datetime when a new record is added - just to keep the logs.

Now we have a stored procedure that will add a new employee record:

 CREATE PROCEDURE spAddNewEmployee
                @FirstName AS VARCHAR(50),
                @LASTNAME AS VARCHAR(50),
                @DATEOFBIRTH AS DATETIME            
    AS
    BEGIN
        -- SET NOCOUNT ON added to prevent extra result sets from
        -- interfering with SELECT statements.
        SET NOCOUNT ON;

        -- Insert statements for procedure here

    DECLARE @LAST_SEQUENCE_NUMBER AS INT;

    SELECT @LAST_SEQUENCE_NUMBER   = MAX([SequenceNumber]) FROM dbo.Employee

    IF(@LAST_SEQUENCE_NUMBER IS NULL)
    BEGIN
        SET @LAST_SEQUENCE_NUMBER = 1;
    END
    ELSE
    BEGIN
        SET @LAST_SEQUENCE_NUMBER = @LAST_SEQUENCE_NUMBER + 1

    END


    INSERT INTO dbo.Employee
    (
           [FirstName]
          ,[LastName]
          ,[DateOfBirth]
          ,[SequenceNumber]      
    )
    VALUES
    (
        @FirstName,
        @LastName,
        @DateOfBirth,
        @LAST_SEQUENCE_NUMBER
    )
    END
    GO

It will retrieve the last SequenceNumber value if its not null (which will be when first record will be added) it will add 1 to it. Next the record will be added along with the auto field DateTimeStamp.

So far so good. Now lets get to the Delete employee part, here is the Delete Employee stored proc:

CREATE PROCEDURE [dbo].[spDeleteEmployee]
                @EmployeeId  AS INT 
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

    -- Insert statements for procedure here

    DECLARE @DELETED_SEQUENCE_NUMBER AS INT, @LAST_SEQUENCE_NUMBER AS INT;

    SELECT @LAST_SEQUENCE_NUMBER   =  MAX([SequenceNumber]) FROM dbo.Employee
    SELECT @DELETED_SEQUENCE_NUMBER   = [SequenceNumber] FROM dbo.Employee WHERE ID = @EMPLOYEEID

    DELETE FROM dbo.Employee
    WHERE ID = @EMPLOYEEID

    WHILE(@DELETED_SEQUENCE_NUMBER   <= @LAST_SEQUENCE_NUMBER)
    BEGIN
        UPDATE dbo.Employee
        SET SequenceNumber = @DELETED_SEQUENCE_NUMBER
        WHERE SequenceNumber = @DELETED_SEQUENCE_NUMBER + 1

        SET @DELETED_SEQUENCE_NUMBER = @DELETED_SEQUENCE_NUMBER + 1
    END


END

GO

To keep the SequenceNumber constant incremental first we are getting the last sequence number and the one which is being deleted. Then after deleting the record, we are looping through each record that comes after the deleted one and aligning the SequenceNumber until we reach to the end of the records ie while loop condition.

To make it better, you can use of transaction to encapsulate the whole operation.

EDIT: You can also make SequenceNumber column unique:

 ALTER TABLE [dbo].[Employee] ADD CONSTRAINT UQ_SequenceNumber UNIQUE ([SequenceNumber])

Hope this answers your question.

Answer 2

In my opinion, if you just want to display the sequential numbers in the Gridview, you don't need to bother about the underlying Auto Increment Primary Key.

You can use <%# Container.DataItemIndex + 1 %> to display that sequential number.

Please see the example below:

<asp:GridView ID="GridView1" runat="server"  AutoGenerateColumns="False" >
<Columns>
        <asp:TemplateField HeaderText="#">
            <ItemTemplate>
                <%# Container.DataItemIndex + 1 %>
            </ItemTemplate>
            <ItemStyle Font-Bold="false" />
        </asp:TemplateField>
        <asp:BoundField DataField="FirstName" HeaderText="FirstName"></asp:BoundField>
        <asp:BoundField DataField="LastName" HeaderText="LastName"></asp:BoundField>
</Columns>
</asp:GridView>