Returns the length of the expression in bytes.
| Parameter | Description | 
|---|---|
| expression | The expression is usually a column name. If the expression is a string constant, it must be enclosed in quotes. | 
UNSIGNED INT
| Data type | DATALENGTH | 
|---|---|
| SMALLINT | 2 | 
| INTEGER | 4 | 
| DOUBLE | 8 | 
| CHAR | Length of the data | 
| BINARY | Length of the data |