How Can SQL Server Sequences Generate Unique Sequential Values Efficiently?

Implementing Sequences in SQL Server

Many applications require the ability to generate unique, sequential values for various purposes. While GUIDs can be used, they may not be ideal in all cases. Additionally, inserting and retrieving values through separate queries can be inefficient.

The Solution: Sequences

SQL Server 2012 introduced SEQUENCE objects specifically designed for this purpose. These objects allow the creation of sequential numeric values independently of any table.

Creating a Sequence

Creating a sequence is straightforward:

CREATE SEQUENCE Schema.SequenceName
AS int
INCREMENT BY 1 ;

This will create a sequence named SequenceName that generates sequential integer values, incrementing by 1.

Using Sequences

To use a sequence, simply call the NEXT VALUE FOR function to retrieve the next available value:

DECLARE @NextID int ;
SET @NextID = NEXT VALUE FOR Schema.SequenceName;
-- Some work happens
INSERT Schema.Orders (OrderID, Name, Qty)
  VALUES (@NextID, 'Rim', 2) ;

In this example, the next value from the SequenceName sequence is retrieved and used as the OrderID for a new record in the Orders table.

Sequences provide a reliable and efficient way to generate sequential values in SQL Server, eliminating the need for cumbersome workarounds.

The above is the detailed content of How Can SQL Server Sequences Generate Unique Sequential Values Efficiently?. For more information, please follow other related articles on the PHP Chinese website!