New Guid in SQL Server

Hello Dev, welcome to our journal article about the new Guid in SQL Server. In this article, we will discuss the basics of Guid and its implementation in SQL Server. Let’s dive in!

What is Guid?

A Guid or a Globally Unique Identifier is a 128-bit value that is guaranteed to be unique across all computers and networks. Guids are commonly used to identify entities in computer systems, such as records in databases, files, and objects in programming languages.

Guids are randomly generated and consist of hexadecimal digits, separated by hyphens in a specific pattern. The uniqueness of Guids is guaranteed by the vastness of the number space, making the probability of generating the same Guid twice virtually impossible.

Implementation of Guid in SQL Server

SQL Server has supported Guids as a data type for a long time. However, the implementation of Guids in SQL Server has gone through significant changes in the recent past. In this section, we will discuss the new Guid implementation in SQL Server.

Newsequentialid()

The newsequentialid() function is a new Guid implementation added in SQL Server 2005. This function generates Guids in sequential order, thereby improving the performance of insert operations for tables that use Guid as a primary key.

The newsequentialid() function is similar to the newid() function, which generates random Guids. However, newsequentialid() generates Guids in a sequential sequence using the MAC address of the computer as the seed value.

The newsequentialid() function returns a uniqueidentifier data type, and the Guids generated using this function are compatible with Guids generated using the newid() function.

Using Guid in SQL Server

Guids are commonly used in SQL Server as primary keys for tables, instead of traditional identity columns. This is because Guids are unique across all computers and networks, making them ideal for distributed systems.

To use Guids as primary keys in SQL Server, you need to create a column of the uniqueidentifier data type and set the default value of the column to newsequentialid(). You can then use the Guids generated by the default value to insert new records into the table.

Advantages of Using Guids

There are several advantages of using Guids in SQL Server:

Uniqueness

As mentioned earlier, Guids are guaranteed to be unique across all computers and networks. This makes them ideal for distributed systems where multiple instances of an application may generate new records simultaneously.

No Collision

The probability of generating the same Guid twice is virtually impossible due to the vastness of the number space. This ensures that there are no collisions, which can be a problem with traditional identity columns.

Security

Guids can also be used for security purposes, such as generating authentication tokens and session identifiers. Since Guids are unique and random, they are difficult to guess, making them ideal for security applications.

Performance

Newsequentialid() generates Guids in a sequential sequence, making it ideal for tables that use Guid as a primary key. This improves the performance of insert operations compared to traditional identity columns.

Creating Tables with Guids

Creating tables with Guids is straightforward in SQL Server. In this section, we will show you how to create a table with a Guid primary key.

Example

Column Name	Data Type	Constraints
Id	uniqueidentifier	PRIMARY KEY DEFAULT newsequentialid()
Name	varchar(50)	NOT NULL
Age	int	NOT NULL

In the example above, we have created a table with a Guid primary key using the uniqueidentifier data type. The primary key constraint is set to default to newsequentialid(), which generates a new Guid on each insert operation.

The Name and Age columns are standard columns with their respective data types and constraints.

Frequently Asked Questions

What are Guids?

Guids or Globally Unique Identifiers are 128-bit values that are guaranteed to be unique across all computers and networks. They are commonly used to identify entities in computer systems, such as records in databases, files, and objects in programming languages.

What is newsequentialid() in SQL Server?

Newsequentialid() is a function in SQL Server that generates Guids in sequential order, using the MAC address of the computer as the seed value. This function is commonly used for tables that use Guid as a primary key and improves the performance of insert operations.

How to create a table with a Guid primary key?

To create a table with a Guid primary key, you need to create a column of the uniqueidentifier data type and set the default value of the column to newsequentialid(). You can then use the Guids generated by the default value to insert new records into the table.

Why use Guids in SQL Server?

Guids are commonly used in SQL Server as primary keys for tables because they are unique across all computers and networks, making them ideal for distributed systems. They also offer security benefits and can improve performance compared to traditional identity columns.