---
title: "DATABASE_PRINCIPAL_ID (Transact-SQL) | Microsoft Docs"
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  - "DATABASE_PRINCIPAL_ID_TSQL"
  - "DATABASE_PRINCIPAL_ID"
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  - "identification numbers [SQL Server], principals"
  - "principal ID numbers [SQL Server]"
  - "DATABASE_PRINCIPAL_ID function"
  - "IDs [SQL Server], principals"
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---
# DATABASE_PRINCIPAL_ID (Transact-SQL)
[!INCLUDE[tsql-appliesto-ss2008-asdb-xxxx-xxx-md](../../includes/tsql-appliesto-ss2008-asdb-xxxx-xxx-md.md)]

Returns the ID number of a principal in the current database. For more information about principals, see [Principals (Database Engine)](../../relational-databases/security/authentication-access/principals-database-engine.md).
  
![Topic link icon](../../database-engine/configure-windows/media/topic-link.gif "Topic link icon") [Transact-SQL Syntax Conventions](../../t-sql/language-elements/transact-sql-syntax-conventions-transact-sql.md)
  
## Syntax  
  
```sql
DATABASE_PRINCIPAL_ID ( 'principal_name' )  
```  
  
## Arguments  
*principal_name*  
Is an expression of type **sysname** that represents the principal.  
When *principal_name* is omitted, the ID of the current user is returned. The parentheses are required.
  
## Return types
**int**  
NULL when the database principal does not exist
  
## Remarks  
DATABASE_PRINCIPAL_ID can be used in a select list, a WHERE clause, or anywhere an expression is allowed. For more information, see [Expressions (Transact-SQL)](../../t-sql/language-elements/expressions-transact-sql.md).
  
## Examples  
  
### A. Retrieving the ID of the current user  
The following example returns the database principal ID of the current user.
  
```sql
SELECT DATABASE_PRINCIPAL_ID();  
GO  
```  
  
### B. Retrieving the ID of a specified database principal  
The following example returns the database principal ID for the database role `db_owner`.
  
```sql
SELECT DATABASE_PRINCIPAL_ID('db_owner');  
GO  
```  
  
## See also
[Principals (Database Engine)](../../relational-databases/security/authentication-access/principals-database-engine.md)  
[Permissions Hierarchy (Database Engine)](../../relational-databases/security/permissions-hierarchy-database-engine.md)  
[sys.database_principals (Transact-SQL)](../../relational-databases/system-catalog-views/sys-database-principals-transact-sql.md)