Question

I have a column, which stores a 4 character long string with 4 or less wild characters (for eg. ????, ??01‘, 0??1 etc). For each such string like 0??1 I have to insert into another table values 0001 to 0991; for the string ??01, values will be be 0001 to 9901; for string ???? values will be 0000 to 9999 and so on.

How could I accomplish this using PL/SQL and string functions?

EDIT

The current code is:

declare 

  v_rule varchar2(50) := '????52132'; 
  v_cc varchar2(50); 
  v_nat varchar2(50); 
  v_wild number; 
  n number; 

begin 

  v_cc := substr(v_rule,1,4); 
  v_nat := substr(v_rule,5); 

  dbms_output.put_line (v_cc || ' '|| v_nat); 

  if instr(v_cc, '????') <> 0 then 
    v_wild := 4; 
  end if; 

  n := power(10,v_wild); 

  for i in 0 .. n - 1 loop 
    dbms_output.put_line(substr(lpad(to_char(i),v_wild,'0' ),0,4)); 
  end loop; 

end;
/

Answer 1

Would something like the following help?

BEGIN
  FOR source_row IN (SELECT rule FROM some_table)
  LOOP
    INSERT INTO some_other_table (rule_match)
      WITH numbers AS (SELECT LPAD(LEVEL - 1, 4, '0') AS num FROM DUAL CONNECT BY LEVEL <= 10000)
      SELECT num FROM numbers WHERE num LIKE REPLACE(source_row.rule, '?', '_');
  END LOOP;
END;
/

This assumes you have a table called some_table with a column rule, which contains text such as ??01, 0??1 and ????. It inserts into some_other_table all numbers from 0000 to 9999 that match these wild-carded patterns.

The subquery

SELECT LPAD(LEVEL - 1, 4, '0') AS num FROM DUAL CONNECT BY LEVEL <= 10000)

generates all numbers in the range 0000 to 9999. We then filter out from this list of numbers any that match this pattern, using LIKE. Note that _ is the single-character wildcard when using LIKE, not ?.

I set this up with the following data:

CREATE TABLE some_table (rule VARCHAR2(4));

INSERT INTO some_table (rule) VALUES ('??01');
INSERT INTO some_table (rule) VALUES ('0??1');
INSERT INTO some_table (rule) VALUES ('????');
COMMIT;

CREATE TABLE some_other_table (rule_match VARCHAR2(4));

After running the above PL/SQL block, the table some_other_table had 10200 rows in it, all the numbers that matched all three of the patterns given.