Sql Server Generate Guid Primary Key

13.04.202013.04.2020

Sql Server Generate Guid Primary Key In Excel
Sql Server Generate Guid Primary Key Example

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APPLIES TO: SQL Server Azure SQL Database Azure Synapse Analytics (SQL DW) Parallel Data Warehouse

Globally Unique Identifier’s are sometimes used as Primary Keys. GUIDs are in-fact the best choice in replicated scenarios, when you have to generate unique values at different locations. GUIDs are being generated by the SQL code or by a column default, rather than. Nov 19, 2015 One of the first steps in creating any database table is deciding what kind of data will uniquely identify a given row in said table; we call this a primary key.In modern databases, if we want to create a unique key from 'thin air' and not use already-existing data (this situation is known as using a surrogate key) we have two commonly-accepted options: using integers, or using Globally-Unique.

Creates a unique value of type uniqueidentifier.

Syntax

Return Types

uniqueidentifier

Remarks

NEWID() is compliant with RFC4122.

Examples

A. Using the NEWID function with a variable

The following example uses NEWID() to assign a value to a variable declared as the uniqueidentifier data type. The value of the uniqueidentifier data type variable is printed before the value is tested.

Here is the result set.

Note

The value returned by NEWID is different for each computer. This number is shown only for illustration.

B. Using NEWID in a CREATE TABLE statement

Applies to: SQL Server

The following example creates the cust table with a uniqueidentifier data type, and uses NEWID to fill the table with a default value. In assigning the default value of NEWID(), each new and existing row has a unique value for the CustomerID column.

C. Using uniqueidentifier and variable assignment

The following example declares a local variable called @myid as a variable of uniqueidentifier data type. Then, the variable is assigned a value by using the SET statement.

SQL PRIMARY KEY Constraint

The PRIMARY KEY constraint uniquely identifies each record in a table.

Primary keys must contain UNIQUE values, and cannot contain NULL values.

A table can have only ONE primary key; and in the table, this primary key can consist of single or multiple columns (fields).

SQL PRIMARY KEY on CREATE TABLE

The following SQL creates a PRIMARY KEY on the 'ID' column when the 'Persons' table is created:

MySQL:

CREATE TABLE Persons (
ID int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int,
PRIMARY KEY (ID)
);

SQL Server / Oracle / MS Access:

CREATE TABLE Persons (
ID int NOT NULL PRIMARY KEY,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int
);

To allow naming of a PRIMARY KEY constraint, and for defining a PRIMARY KEY constraint on multiple columns, use the following SQL syntax:

MySQL / SQL Server / Oracle / MS Access: Steam product code.

CREATE TABLE Persons (
ID int NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int,
CONSTRAINT PK_Person PRIMARY KEY (ID,LastName)
);

Note: In the example above there is only ONE PRIMARY KEY (PK_Person). However, the VALUE of the primary key is made up of TWO COLUMNS (ID + LastName).

SQL PRIMARY KEY on ALTER TABLE

To create a PRIMARY KEY constraint on the 'ID' column when the table is already created, use the following SQL:

MySQL / SQL Server / Oracle / MS Access:

To allow naming of a PRIMARY KEY constraint, and for defining a PRIMARY KEY constraint on multiple columns, use the following SQL syntax:

MySQL / SQL Server / Oracle / MS Access:

ALTER TABLE Persons
ADD CONSTRAINT PK_Person PRIMARY KEY (ID,LastName);

Note: If you use the ALTER TABLE statement to add a primary key, the primary key column(s) must already have been declared to not contain NULL values (when the table was first created).