Returns the number of bytes used to represent any expression.
DATALENGTH ( expression )
expression
Is an expression of any type.
int
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 sp_dbcmptlevel.
This example finds the length of the pub_name column in the publishers table.
USE pubs
GO
SELECT length = DATALENGTH(pub_name), pub_name
FROM publishers
ORDER BY pub_name
GO
Here is the result set:
length pub_name
----------- ----------------------------------------
20 Algodata Infosystems
16 Binnet & Hardley
21 Five Lakes Publishing
5 GGG&G
18 Lucerne Publishing
14 New Moon Books
17 Ramona Publishers
14 Scootney Books
(8 row(s) affected)