Menu
-->APPLIES TO: SQL Server Azure SQL Database Azure Synapse Analytics (SQL DW) Parallel Data Warehouse APPLIES TO: SQL Server 2016 and later Azure SQL Database Azure Synapse Analytics (SQL DW) Parallel Data Warehouse
- Sql Server Guid Primary Key
- Sql Server Guid Data Type
- Sql Server Generate Guid Primary Key Id
- Sql Server Auto Generated Guid Primary Key
- Sql Server Generate Guid Primary Key Example
- Sql Server Generate Guid Primary Key Tutorial
Sql Server Guid Primary Key
May 03, 2018 To create a GUID in SQL Server, the NEWID function is used as shown below: 1 SELECT NEWID Execute the above line of SQL multiple times and you will see a different value every time. Mar 19, 2007 The Cost of GUIDs as Primary Keys (SQL Server 2000) Myths, GUID vs. Autoincrement (MySQL 5) Using a GUID as a row identity value feels more natural- and certainly more truly unique- than a 32-bit integer. Database guru Joe Celko seems to agree. GUID primary keys are a natural fit for many development scenarios, such as replication, or when. Using SQL Server GUID as primary key. Sometimes, it prefers using GUID values for the primary key column of a table than using integers. Using GUID as the primary key of a table brings the following advantages: GUID values are globally unique across tables, databases, and even servers. Is it worth having both int and guid in the table or should I just drop the int entirely? Yes, from the perspective that you can have the identity column be a unique clustered index to take advantage of inserts being append-only to the table, and you can have a nonclustered primary key on your GUID column for both security and uniqueness when locating records.
Creates a unique value of type uniqueidentifier.
Syntax
Return Types
uniqueidentifier
Remarks
NEWID()
is compliant with RFC4122.Examples
Sql Server Guid Data Type
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.See Also
NEWSEQUENTIALID (Transact-SQL)
ALTER TABLE (Transact-SQL)
CAST and CONVERT (Transact-SQL)
CREATE TABLE (Transact-SQL)
Data Types (Transact-SQL)
System Functions (Transact-SQL)
uniqueidentifier (Transact-SQL)
Sequence Numbers
ALTER TABLE (Transact-SQL)
CAST and CONVERT (Transact-SQL)
CREATE TABLE (Transact-SQL)
Data Types (Transact-SQL)
System Functions (Transact-SQL)
uniqueidentifier (Transact-SQL)
Sequence Numbers
-->
You can define a primary key in SQL Server by using SQL Server Management Studio or Transact-SQL. Creating a primary key automatically creates a corresponding unique clustered index, or a nonclustered index if specified as such.
Before You Begin
Limitations and Restrictions
- A table can contain only one PRIMARY KEY constraint.
- All columns defined within a PRIMARY KEY constraint must be defined as NOT NULL. If nullability is not specified, all columns participating in a PRIMARY KEY constraint have their nullability set to NOT NULL.
Sql Server Generate Guid Primary Key Id
Security
Permissions
Creating a new table with a primary key requires CREATE TABLE permission in the database and ALTER permission on the schema in which the table is being created.
Creating a primary key in an existing table requires ALTER permission on the table.
Using SQL Server Management Studio
To create a primary key
- In Object Explorer, right-click the table to which you want to add a unique constraint, and click Design.
- In Table Designer, click the row selector for the database column you want to define as the primary key. If you want to select multiple columns, hold down the CTRL key while you click the row selectors for the other columns.
- Right-click the row selector for the column and select Set Primary Key.
Caution
If you want to redefine the primary key, any relationships to the existing primary key must be deleted before the new primary key can be created. A message will warn you that existing relationships will be automatically deleted as part of this process.
A primary key column is identified by a primary key symbol in its row selector.
Sql Server Auto Generated Guid Primary Key
If a primary key consists of more than one column, duplicate values are allowed in one column, but each combination of values from all the columns in the primary key must be unique.
Sql Server Generate Guid Primary Key Example
If you define a compound key, the order of columns in the primary key matches the order of columns as shown in the table. However, you can change the order of columns after the primary key is created. For more information, see Modify Primary Keys.
Using Transact-SQL
To create a primary key in an existing table
The following example creates a primary key on the column
TransactionID
in the AdventureWorks database.To create a primary key in a new table
The following example creates a table and defines a primary key on the column
TransactionID
in the AdventureWorks database.To create a primary key with clustered index in a new table
Sql Server Generate Guid Primary Key Tutorial
The following example creates a table and defines a primary key on the column
CustomerID
and a clustered index on TransactionID
in the AdventureWorks database.