The actual length of the result is the length of the expression minus the number of characters removed. If all the characters
are removed, the result is an empty string.
If the parameter can be null, the result can be null.
If the parameter is null, the result is the null value.
The TRIM specifications defined by the SQL/2008 standard (LEADING and TRAILING) are supplied by the SQL Anywhere LTRIM and
RTRIM functions respectively.