The DIGITS function returns a character-string representation of a number.
The argument must be an expression that returns a value of type SMALLINT, INTEGER, BIGINT or DECIMAL.
If the argument can be null, the result can be null; if the argument is null, the result is the null value.
The result of the function is a fixed-length character string representing the absolute value of the argument without regard to its scale. The result does not include a sign or a decimal character. Instead, it consists exclusively of digits, including, if necessary, leading zeros to fill out the string. The length of the string is:
·5 if the argument is a small integer
·10 if the argument is a large integer
·19 if the argument is a big integer
·p if the argument is a decimal number with a precision of p.
digits函数返回一个代表数字的字符串。
参数必须是一个表达式 ,返回整形,samllint,integer,bigint or decimal.