LENGTH(a)

LENGTH(a) is an arithmetic function that specifies the number of characters or bytes that are required to represent the expression a internally. The function can be applied to all data types (including LOB).

LENGTH(a)
a	Result of the LENGTH(a) function
`a` is a value of data type CHAR \| VARCHAR `<ASCII\|UNICODE>` with `n` characters	Number of characters `n`
`a` is a value of a different data type of length `n`	Length `n` in `Bytes`
`a` is a NULL value	`NULL` value
`a` is a special NULL value	Special `NULL` value

The number of characters or the length in bytes is determined without taking into account any trailing blank characters (code attribute ASCII, UNICODE) or binary zeros (code attribute BYTE).

Example

SQL Tutorial, Information About Character Strings