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title: "sys.fn_cdc_is_bit_set (Transact-SQL) | Microsoft Docs"
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# sys.fn_cdc_is_bit_set (Transact-SQL)
[!INCLUDE[tsql-appliesto-ss2008-xxxx-xxxx-xxx_md](../../includes/tsql-appliesto-ss2008-xxxx-xxxx-xxx-md.md)]

  Indicates whether a captured column has been updated by checking whether its ordinal position is set within a provided bitmask.  
  
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|**Applies to**: [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] ([!INCLUDE[ssKatmai](../../includes/sskatmai-md.md)] through [current version](http://go.microsoft.com/fwlink/p/?LinkId=299658)).|  
  
 ![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  
  
```  
  
sys.fn_cdc_is_bit_set ( position , update_mask )  
```  
  
## Arguments  
 *position*  
 Is the ordinal position in the mask to check. *position* is **int**.  
  
 *update_mask*  
 Is the mask identifying updated columns. *update_mask* is **varbinary(128)**.  
  
## Return Type  
 **bit**  
  
## Remarks  
 This function is typically used as part of a change data query to indicate whether a column has changed. In this scenario, the function [sys.fn_cdc_get_column_ordinal](../../relational-databases/system-functions/sys-fn-cdc-get-column-ordinal-transact-sql.md) is used before the query to obtain the required column ordinal. **sys.fn_cdc_is_bit_set** is then applied to each row of change data that is returned, providing the column-specific information as part of the returned result set.  
  
 We recommend using this function instead of the function [sys.fn_cdc_has_column_changed](../../relational-databases/system-functions/sys-fn-cdc-has-column-changed-transact-sql.md) when determining whether columns have changed for all rows of a returned result set.  
  
## Permissions  
 Requires membership in the **public** role.  
  
## Examples  
 The following example uses `sys.fn_cdc_is_bit_set` to prepend to the result set generated by the query function `cdc.fn_cdc_get_all_changes_HR_Department` the column '`IsGroupNmUpdated`' using the precomputed column ordinal and the value of `__$update_mask` as arguments to the call.  
  
```  
USE AdventureWorks2012;  
GO  
DECLARE @from_lsn binary(10), @to_lsn binary(10), @GroupNm_ordinal int;  
SET @from_lsn = sys.fn_cdc_get_min_lsn('HR_Department');  
SET @to_lsn = sys.fn_cdc_get_max_lsn();  
SET @GroupNm_ordinal = sys.fn_cdc_get_column_ordinal('HR_Department','GroupName');  
  
SELECT sys.fn_cdc_is_bit_set(@GroupNm_ordinal,__$update_mask) as 'IsGroupNmUpdated', *  
FROM cdc.fn_cdc_get_all_changes_HR_Department( @from_lsn, @to_lsn, 'all')  
WHERE __$operation = 4;  
GO  
```  
  
## See Also  
 [Change Data Capture Functions (Transact-SQL)](../../relational-databases/system-functions/change-data-capture-functions-transact-sql.md)   
 [sys.fn_cdc_get_column_ordinal (Transact-SQL)](../../relational-databases/system-functions/sys-fn-cdc-get-column-ordinal-transact-sql.md)   
 [sys.fn_cdc_has_column_changed (Transact-SQL)](../../relational-databases/system-functions/sys-fn-cdc-has-column-changed-transact-sql.md)   
 [cdc.fn_cdc_get_all_changes_<capture_instance>  (Transact-SQL)](../../relational-databases/system-functions/cdc-fn-cdc-get-all-changes-capture-instance-transact-sql.md)   
 [cdc.fn_cdc_get_net_changes_<capture_instance> (Transact-SQL)](../../relational-databases/system-functions/cdc-fn-cdc-get-net-changes-capture-instance-transact-sql.md)   
 [About Change Data Capture (SQL Server)](../../relational-databases/track-changes/about-change-data-capture-sql-server.md)