Returns the defined length, in bytes, of a column.
Returns NULL on error or if a caller does not have permission to view the object.
In SQL Server, a user can only view the metadata of securables that the user owns or on which the user has been granted permission. This means that metadata-emitting, built-in functions such as COL_LENGTH may return NULL if the user does not have any permission on the object. For more information, see Metadata Visibility Configuration.
The following example shows the return values for a column of type varchar(40) and a column of type nvarchar(40).
USE AdventureWorks2012; GO CREATE TABLE t1(c1 varchar(40), c2 nvarchar(40) ); GO SELECT COL_LENGTH('t1','c1')AS 'VarChar', COL_LENGTH('t1','c2')AS 'NVarChar'; GO DROP TABLE t1;
Here is the result set.
VarChar NVarChar 40 80