SQL to find missing gaps

Question

Hi Gurus,
I have a simple SQL question on how to find gaps. I have a Table : GLHDR_M, with ACCID as the key field having Account Ids starting from 'A1000001' to 'A3999999' but having gaps inbetween. I want to reallocate the missing Ids to the newly created ones. How can I find the missing Ids with a simple SQL statement?
Thank you

Answer 1

You can achieve this using pipelined table function like the below
CREATE OR REPLACE TYPE nt_tab IS TABLE OF VARCHAR2(20);
CREATE OR REPLACE FUNCTION fn_piperowgen(v_endval    VARCHAR2,
                                         v_startval  VARCHAR2
RETURN nt_tab PIPELINED
AS
BEGIN
FOR i IN 1..(TO_NUMBER(LTRIM(REPLACE(v_endval,'A'),'0'))-TO_NUMBER(LTRIM(REPLACE(v_startval,'A'),'0'))) + 1
  LOOP
    PIPE ROW('A'||LPAD(TO_NUMBER(LTRIM(REPLACE(v_startval,'A'),'0'))+(i-1),7,'0'));
  END LOOP;
RETURN;
END fn_piperowgen;
SELECT COLUMN_VALUE acid
FROM TABLE(fn_piperowgen('A0904999','A0904000'))
MINUS
SELECT acid
FROM glhdr_m
WHERE acid BETWEEN 'A0904000' AND 'A0904999';
OUTPUT:-
SQL> CREATE OR REPLACE TYPE nt_tab IS TABLE OF VARCHAR2(20);
  2  /
Type created.
SQL> CREATE OR REPLACE FUNCTION fn_piperowgen(v_endval    VARCHAR2,
  2                                           v_startval  VARCHAR2
  3                                                                              )
  4  RETURN nt_tab PIPELINED
  5  AS
  6  BEGIN
  7   FOR i IN 1..(TO_NUMBER(LTRIM(REPLACE(v_endval,'A'),'0'))-TO_NUMBER(LTRIM(REPLACE(v_startval,'A'),'0'))) + 1
  8    LOOP
  9      PIPE ROW('A'||LPAD(TO_NUMBER(LTRIM(REPLACE(v_startval,'A'),'0'))+(i-1),7,'0'));
10    END LOOP;
11  RETURN;
12  END fn_piperowgen;
13  /
Function created.
SQL> SELECT COLUMN_VALUE acid
  2  FROM TABLE(fn_piperowgen('A0904999','A0904000'))
  3  MINUS
  4  SELECT acid
  5  FROM glhdr_m
  6  WHERE acid BETWEEN 'A0904000' AND 'A0904999';
ACID
A0904993
A0904994
A0904995
A0904996
A0904997
A0904998
A0904999
997 rows selected.