LEN (Transact-SQL)

Статия
09/03/2024

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW) SQL analytics endpoint in Microsoft Fabric Warehouse in Microsoft Fabric

Returns the number of characters of the specified string expression, excluding trailing spaces.

Note

To return the number of bytes used to represent an expression, use the DATALENGTH function.

Transact-SQL syntax conventions

Syntax

LEN ( string_expression )

Arguments

string_expression
Is the string expression to be evaluated. string_expression can be a constant, variable, or column of either character or binary data.

Return Types

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

If you are using SC collations, the returned integer value counts UTF-16 surrogate pairs as a single character. For more information, see Collation and Unicode Support.

Remarks

LEN excludes trailing spaces. If that is a problem, consider using the DATALENGTH (Transact-SQL) function which does not trim the string. If processing a unicode string, DATALENGTH will return a number that may not be equal to the number of characters. The following example demonstrates LEN and DATALENGTH with a trailing space.

  DECLARE @v1 VARCHAR(40),  
    @v2 NVARCHAR(40);  
SELECT   
@v1 = 'Test of 22 characters ',   
@v2 = 'Test of 22 characters ';  
SELECT LEN(@v1) AS [VARCHAR LEN] , DATALENGTH(@v1) AS [VARCHAR DATALENGTH];  
SELECT LEN(@v2) AS [NVARCHAR LEN], DATALENGTH(@v2) AS [NVARCHAR DATALENGTH];

Note

Use the LEN to return the number of characters encoded into a given string expression, and DATALENGTH to return the size in bytes for a given string expression. These outputs may differ depending on the data type and type of encoding used in the column. For more information on storage differences between different encoding types, see Collation and Unicode Support.

Examples

The following example selects the number of characters and the data in FirstName for people located in Australia. This example uses the AdventureWorks database.

SELECT LEN(FirstName) AS Length, FirstName, LastName   
FROM Sales.vIndividualCustomer  
WHERE CountryRegionName = 'Australia';  
GO

Examples: Azure Synapse Analytics and Analytics Platform System (PDW)

The following example returns the number of characters in the column FirstName and the first and last names of employees located in Australia.

USE AdventureWorks2022  
GO  
SELECT DISTINCT LEN(FirstName) AS FNameLength, FirstName, LastName   
FROM dbo.DimEmployee AS e  
INNER JOIN dbo.DimGeography AS g   
    ON e.SalesTerritoryKey = g.SalesTerritoryKey   
WHERE EnglishCountryRegionName = 'Australia';

Here's the result set.

FNameLength  FirstName  LastName  
-----------  ---------  ---------------  
4            Lynn       Tsoflias

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