Asp.Net Sql Auto-Increment for Wall Post - asp.net

Question

I have a table that contains three columns.
"UserId" type-nvarchar
"PostAuthorId" type-nvarchar
"Post" type-text
This table will contain "wall" posts like in facebook for each user's page. I am going to use a gridview on each user's page to display the posts. The issue is I want to display them with the latest(most current) post being first and the earliest post being last.
I have never used autoincrement before and I am not sure if that is the answer. If it is, I do not know how to use it. I thought about adding a date posted column and then ordering by date.
If I end up using the date column, I could also display the date on the post. Is there a way to convert the date to a readable format?
What is the best way of implementing this type of ordering?

Answer 1

If you use AutoIcrement the first record will start with 1 and each record will increment from there. (default setting)
If you want to sort them by newest first do an ORDER BY ID DESC
I would suggest making a column called wallPostID then setting that to AutoIncrement and also your Primary Key
Date Formating:
If you are displaying this data in a gridView
Go to Edit Columns on your grid view
CLick on the Date field under "Selected Fields" on the bottom left
Under "BoundField properties" on the right Go to Data -> DataFormatString
{0:d} will display as 1/1/2010
This site has more info in string formatting
http://msdn.microsoft.com/en-us/library/fht0f5be.aspx

Answer 2

A datetime column would definitely work for something like this. Assuming you are using MS-SQL, you can also attach a default value to the column using a built-in function like GETDATE(). That way, you only have to input the data that matters and the database will take care of adding the datetime column.

Answer 3

For converting a datetime to a readable format try:
DateTime postDate;
string value = postDate.ToShortDateString();

Answer 4

You should always use an ID field that auto increments. Can also be used as your PK

Answer 5

I would suggest the DateTime field rather than the autoincrement simply because it will not only serve as an effective Sort field, it also preserves information that you may well want to display. If you want the most recent first you'll sort using the Date and a "DESC" modifier:
Select ... Order By [Date] DESC;
When you retrieve the data, you can retrieve it as a DateTime and modify it using C#. You can use "ToShortDateString()" as suggested by mdresser if you just wish to show the date or ToString("...") if you wish to show the time as well. You can also use SQL to convert it into a string before retrieving it:
convert(Varchar(10), #mydatetime, 101)
If you look in MSDN you'll see the various conversion codes (101 is the code used above) that can be used to translate the date in various ways.
UPDATE: You may want to use an autoincrementing field for your application for reasons other than your expressed need to sort wall entries. They are easy to use - just mark the field as an Identity if using SQL Server (other DBs are similar). As far as using them in your program, just think of the field as an Int field that you never have to set.
Now, why would you use a auto-incrementing field? Perhaps the most straightforward reason is so that they give you have an easy way to identify each record. For example, if you permit people to alter or delete their wall entries, the auto-incrementing field is ideal as it gives you a way to easily look up each record (each record will be assigned its own, unique value). You might put an "x" next to the record like StackOverflow does and make it a call back with the UID (auto-increment) value. Note that you should set up your primary key on the UID field if you'll be doing this.
Now, if you find them useful for this reason then you could also sort by the UID. I would still store the date so that you can provide Date and Time feedback as to when an entry was made on the wall but this would no longer be your indexed or sorted field.