Select the last row in a SQL table - sql

Question

Is it possible to return the last row of a table in MS SQL Server.
I am using an auto increment field for the ID and i want to get the last one just added to join it with something else. Any idea?
Here's the code:
const string QUERY = #"INSERT INTO Questions (ID, Question, Answer, CategoryID, Permission) "
+ #"VALUES (#ID, #Question, #Answer, #CategoryID, #Permission) ";
using (var cmd = new SqlCommand(QUERY, conn))
{
cmd.Parameters.AddWithValue("#Question", question);
cmd.Parameters.AddWithValue("#Answer", answer);
cmd.Parameters.AddWithValue("#CategoryID", lastEdited);
cmd.Parameters.AddWithValue("#Permission", categoryID);
cmd.ExecuteNonQuery();
}

Answer 1

Not safe - could have multiple inserts going on at the same time and the last row you'd get might not be yours. You're better off using SCOPE_IDENTITY() to get the last key assigned for your transaction.

Answer 2

using an auto increment field ... and i want to get the last one just added to join it with something else.
The key here is "just added". If you have a bunch of different users hit the db at the same time, I don't think you want user A to retrieve the record created by user B. That means you probably want to use the scope_identity() function to get that id rather than running a query on the table again right away.
Depending on the context you might also need ##identity (would include triggers) or ident_current('questions') (limited to a specific table, but not the specific scope). But scope_identity() is almost always the right one to use.
Here's an example:
DECLARE #NewOrderID int
INSERT INTO TABLE [Orders] (CustomerID) VALUES (1234)
SELECT #NewOrderID=scope_identity()
INSERT INTO TABLE [OrderLines] (OrderID, ProductID, Quantity)
SELECT #NewOrderID, ProductID, Quantity
FROM [ShoppingCart]
WHERE CustomerID=1234 AND SessionKey=4321
Based on the code you posted, you can do something like this:
// don't list the ID column: it should be an identity column that sql server will handle for you
const string QUERY = "INSERT INTO Questions (Question, Answer, CategoryID, Permission) "
+ "VALUES (#Question, #Answer, #CategoryID, #Permission);"
+ "SELECT scope_identity();";
int NewQuestionID;
using (var cmd = new SqlCommand(QUERY, conn))
{
cmd.Parameters.AddWithValue("#Question", question);
cmd.Parameters.AddWithValue("#Answer", answer);
cmd.Parameters.AddWithValue("#CategoryID", lastEdited);
cmd.Parameters.AddWithValue("#Permission", categoryID);
NewQuestionID = (int)cmd.ExecuteScalar();
}
See my answer to another question here:
get new SQL record ID
The problem now is that you'll likely want subsequent sql statements to be in the same transaction. You could do this with client code, but I find keeping it all on the server to be cleaner. You could do that by building a very long sql string, but I tend to prefer a stored procedure at this point.
I'm also not a fan of the .AddWithValue() method — I prefer explicitly defining the parameter types — but we can leave that for another day.
Finally, it's kind of late now, but I want to emphasize that it's really better to try to keep this all on the db. It's okay to run multiple statements in one sql command, and you want to reduce the number of round trips you need to make to the db and the amount of data you need to pass back and forth between the db and your app. It also makes it easier to get the transactions right and keep things atomic where they need to be.

Answer 3

use
scope_identity() returns the last identity value generated in this session and this scope
ident_current() returns the last identity value generated for a particular table in any session and any scope
select ident_current( 'yourTableName' )
will return the last identity created by a different session.
Most of the time you should use scope_identity() right after an insert statement like so.
--insert statement
SET #id = CAST(SCOPE_IDENTITY() AS INT)
MSDN Link - Scope_Identity()
MSDN Link - Ident_Current

Answer 4

select top 1 * from yourtable order by id desc

Answer 5

I'm not sure of your version of SQL Server, but look for the OUTPUT clause of ther INSERT statement. You can capture a set of rows with this clause

Answer 6

Since the questioner is using .NET, here's a modified example of how to do it. (I removed ID from the insert list since it's autoincrement--the original example would fail. I also assume ID is an SQL int, not a bigint.)
const string QUERY = #"INSERT INTO Questions (Question, Answer, CategoryID, Permission) "
+ #"VALUES (#Question, #Answer, #CategoryID, #Permission);"
+ #"SELECT #ID = SCOPE_IDENTITY();";
using (var cmd = new SqlCommand(QUERY, conn))
{
cmd.Parameters.AddWithValue("#Question", question);
cmd.Parameters.AddWithValue("#Answer", answer);
cmd.Parameters.AddWithValue("#CategoryID", lastEdited);
cmd.Parameters.AddWithValue("#Permission", categoryID);
cmd.Parameters.Add("#ID", System.Data.SqlDbType.Int).Direction = ParameterDirection.Output;
cmd.ExecuteNonQuery();
int id = (int)cmd.Parameters["#ID"].Value;
}
EDITED: I also suggest considering LINQ to SQL instead of hand-coding SqlCommand objects--it's much better (faster to code, easier to use) for many common scenarios.

Answer 7

With a simple select you can do something like this:
SELECT *
FROM table_name
WHERE IDColumn=(SELECT max(IDColum) FROM table_name)