The schema is SYSIBM.
The DIGITS function returns a character-string representation of a number.
The expression must return a value that is a SMALLINT, INTEGER, BIGINT, DECIMAL, CHAR, or VARCHAR data type. In a Unicode database, if a supplied argument is a GRAPHIC or VARGRAPHIC data type, it is first converted to a character string before the function is executed. A CHAR or VARCHAR value is implicitly cast to DECIMAL(31,6) before evaluating the function.
If the argument can be null, the result can be null; if the argument is null, the result is the null value.
Examples:
SELECT DISTINCT SUBSTR(DIGITS(INTCOL),1,4)
FROM TABLEX
DIGITS(COLUMNX)
returns
the value '000628'. The result is a string of length six (the precision of the column) with leading zeros padding the string out to this length. Neither sign nor decimal point appear in the result.