Sorting character column ( used in order by clause dynamically)

Question

Hi,
I need help on sorting character-based numbers. Like say, I want to sort customers based on street numbers(which is a character string being used in the
order by clause) they live in.
The criteria are :
i. Numbers must take precedence.
This being a character string, 1000001 comes before 2. This shouldn't happen. And you cannot use to_number
since using it with a string having characters in it would raise an error.
ii. If only a single alphabet occurs as the last character, then treat the whole string as a number except the last character and then sort it
as if sorting a number. Something like : if you have 1000A, 200D, 200B, 1000X, the result would be 200B,200D,1000A,1000X.
iii. if a character occurs elsewhere in the string, then perform the search normally as if performing a character search.
The output of the following data :
100
A101
B100A
110C
C120B
120
100020
120C
C1100
100D
would be like :
100
100D
110C
120
120C
100020
A101
B100A
C120B
C1100
Please note that the sort is being done dynamically, so I could have access to the values of the street numbers only during run time.
Any help is really appreciated.
Thanks in advance.
Regards,
Anil.

Answer 1

Create a function to test whether the column is numeric :
create FUNCTION is_numeric(v_number VARCHAR2)
RETURN INTEGER
IS
l_number NUMBER;
BEGIN
IF INSTR(UPPER(v_number),'E') > 0 THEN
RETURN 0;
END IF;
l_number := TO_NUMBER(v_number);
RETURN 1;
EXCEPTION
WHEN OTHERS THEN
RETURN 0;
END;
And try this query
Assume the table name is TEST with column STREET
select * from TEST
order by case is_numeric(STREET) when 1 then LPAD(STREET,20, ' ') else STREET end
Please make sure that 20 mentioned above is the column size for STREET.
Hope this helps.
-Nags