Returns the length of the expression in bytes.
DATALENGTH ( expression )
expression The expression is usually a column name. If the expression is a string constant, it must be enclosed in quotes.
Table 4-19 lists the return values of DATALENGTH.
Data type  | 
DATALENGTH  | 
|---|---|
SMALLINT  | 
2  | 
INTEGER  | 
4  | 
DOUBLE  | 
8  | 
CHAR  | 
Length of the data  | 
BINARY  | 
Length of the data  | 
The following statement returns the value 35, the longest string in the company_name column:
SELECT MAX( DATALENGTH( company_name ) ) FROM Customers