datalength-transact-sql.md

title	DATALENGTH (Transact-SQL) | Microsoft Docs
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ms.date	07/29/2017
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f1_keywords	DATALENGTH_TSQL DATALENGTH
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helpviewer_keywords	number of bytes representing expression data types [SQL Server], length DATALENGTH function expressions [SQL Server], length lengths [SQL Server], data
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DATALENGTH (Transact-SQL)

[!INCLUDEtsql-appliesto-ss2008-all_md]

Returns the number of bytes used to represent any expression.

Transact-SQL Syntax Conventions

Syntax

-- Syntax for SQL Server, Azure SQL Database, Azure SQL Data Warehouse, Parallel Data Warehouse  
  
DATALENGTH ( expression )   

Arguments

expression
Is an expression of any data type.

Return types

bigint if expression is of the varchar(max), nvarchar(max) or varbinary(max) data types; otherwise int.

Remarks

DATALENGTH is especially useful with varchar, varbinary, text, image, nvarchar, and ntext data types because these data types can store variable-length data.

The DATALENGTH of NULL is NULL.

Note

Compatibility levels can affect return values. For more information about compatibility levels, see ALTER DATABASE Compatibility Level (Transact-SQL).

Examples

The following example finds the length of the Name column in the Product table.

USE AdventureWorks2012;  
GO  
SELECT length = DATALENGTH(Name), Name  
FROM Production.Product  
ORDER BY Name;  
GO  

Examples: [!INCLUDEssSDWfull] and [!INCLUDEssPDW]

The following example finds the length of the Name column in the Product table.

-- Uses AdventureWorks  
  
SELECT length = DATALENGTH(EnglishProductName), EnglishProductName  
FROM dbo.DimProduct  
ORDER BY EnglishProductName;  
GO  

See also

LEN (Transact-SQL)
CAST and CONVERT (Transact-SQL)
Data Types (Transact-SQL)
System Functions (Transact-SQL)