How Can SQL Server Sequences Simplify Sequential Value Generation?

Implementing Sequences in Microsoft SQL Server

When working with databases, it's often necessary to generate sequential values that are not directly tied to any table or specific data. Traditionally, methods like using GUIDs or inserting a row to retrieve the number could be employed, but these approaches have drawbacks.

Fortunately, SQL Server 2012 introduced SEQUENCE objects that provide a more efficient and structured solution for generating sequential numeric values.

How to Create a SEQUENCE in SQL Server 2012

Creating a SEQUENCE is straightforward:

CREATE SEQUENCE Schema.SequenceName
AS int
INCREMENT BY 1 ;

This command will create a SEQUENCE named SequenceName in the specified schema, with an initial value of 0 and an increment value of 1. Other properties of a SEQUENCE object include its start value and its maximum and minimum values.

Using a SEQUENCE in an INSERT Statement

To utilize a SEQUENCE in your code, you can declare a variable to store the next value in the sequence:

DECLARE @NextID int ;
SET @NextID = NEXT VALUE FOR Schema.SequenceName;

Once you have the next value, you can use it in an INSERT statement:

INSERT Schema.Orders (OrderID, Name, Qty)
  VALUES (@NextID, 'Rim', 2) ;

The number generated by the SEQUENCE object will be automatically inserted into the OrderID column.

Benefits of Using Sequences

Sequences offer several advantages over alternative methods:

• Seamless integration: Sequences are built-in database objects that provide a clean and efficient way to generate sequential values.
• Type safety: Sequences ensure that the generated values conform to the specified data type, reducing data type errors.
• Deterministic ordering: Sequences guarantee that the generated values will be in sequential order, even for concurrent inserts.
• Enhanced performance: Sequences can improve performance by reducing the need for additional database calls to retrieve the latest sequence number.

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