Oracle 11g: How To Select 'Extra' Rows in SQL Query

Question

Using Oracle 11g, and working in an engineering document context, I need to select a collection of rows that include 'extra' rows for prior revs and multiple document sheets.

Specifically, our database has a record for only the latest revision of each engineering document. We need a row returned for each revision and each sheet of these records.

We have data like this:

DRAW_NUM        REV NUM_SHTS
LD-111-639-01   2   3

We Need Data Like This:

DRAW_NUM        REV SHT
LD-111-639-01   1   1
LD-111-639-01   1   2
LD-111-639-01   1   3
LD-111-639-01   2   1
LD-111-639-01   2   2
LD-111-639-01   2   3

My latest SQLPlus query attempt uses an external table to list numbers from 0 to Rev and 0 to Num_Shts, and the code looks like this:

SELECT DISTINCT prefix || '-' || lpad(series,3,0) || '-' || lpad(base,3,0) || '-' || lpad(suffix,2,0) Draw_Num,
(select n from numbers where n >=0 and n <= md_draw.rev) Rv,
(select n from numbers where n >=0 and n <= md_draw.num_shts) Sht
FROM md_draw WHERE Dwg_Date <= TO_DATE('1-JUN-02')
ORDER BY Draw_Num, Rv, Sht
/

But produces the following error:

ORA-01427: single-row subquery returns more than one row

Is there an easy way to do this?

Answer 1

Your two sub-queries are returning multiple rows, you will need to specify which single item you want with either an aggregate function of some kind ( Min() , Max() , etc...):

SELECT DISTINCT prefix || '-' || lpad(series,3,0) || '-' || lpad(base,3,0) || '-' || lpad(suffix,2,0) Draw_Num,
(select Max(n) from numbers where n >=0 and n <= md_draw.rev) Rv,
(select Max(n) from numbers where n >=0 and n <= md_draw.num_shts) Sht
FROM md_draw WHERE Dwg_Date <= TO_DATE('1-JUN-02')
ORDER BY Draw_Num, Rv, Sht

Or, if you need all of them, you should use JOIN s instead of sub-queries:

SELECT DISTINCT prefix || '-' || lpad(series,3,0) || '-' || lpad(base,3,0) || '-' || lpad(suffix,2,0) Draw_Num, 
       n1.n As Rv, n2.n As Shts
FROM md_draw 
JOIN numbers n1 
ON n1.n BETWEEN 0 AND md_draw.rev
JOIN numbers n2
ON n2.n BETWEEN 0 AND md_draw.num_shts
WHERE Dwg_Date <= TO_DATE('1-JUN-02')
ORDER BY Draw_Num, Rv, Sht

You may need to tweak that last query, I didn't have time to run it through sqlfiddle or anything, but it should give you a basic idea of what to do. Just an observation, I don't see what relation both rev and num_shts has to do with n in your numbers table.

Answer 2

That's because of the subquery below which is producing more than 1 row. If there is a relation between md_draw and numbers then consider doing a JOIN

(select n from numbers where n >=0 and n <= md_draw.rev) Rv

Answer 3

Oracle Setup :

CREATE TABLE table_name ( DRAW_NUM, REV, NUM_SHTS ) AS
SELECT 'LD-111-639-01', 2, 3 FROM DUAL UNION ALL
SELECT 'LD-111-639-02', 0, 2 FROM DUAL UNION ALL
SELECT 'LD-111-639-03', 7, 0 FROM DUAL UNION ALL
SELECT 'LD-111-639-04', 1, 2 FROM DUAL;

Query - Using a recursive sub-query factoring clause :

WITH rsqfc ( draw_num, rev, num_shts, rv, sht ) AS (
  SELECT draw_num, rev, num_shts, 1, 1
  FROM   table_name
  WHERE  REV > 0 AND num_shts > 0
UNION ALL
  SELECT draw_num, rev, num_shts,
         CASE sht WHEN num_shts THEN rv+1 ELSE rv END,
         CASE sht WHEN num_shts THEN 1 ELSE sht+1 END
  FROM   rsqfc
  WHERE  rv < rev
  OR     sht < num_shts
)
SELECT draw_num, rv AS rev, sht
FROM   rsqfc
ORDER BY draw_num, rv, sht;

Query - Using Hierarchical Queries :

SELECT t.draw_num,
       r.COLUMN_VALUE AS rev,
       n.COLUMN_VALUE AS sht
FROM   table_name t,
       TABLE(
         CAST(
           MULTISET(
             SELECT LEVEL
             FROM   DUAL
             WHERE  t.REV > 0
             CONNECT BY LEVEL <= t.REV
           ) AS SYS.ODCINUMBERLIST
         )
       ) r,
       TABLE(
         CAST(
           MULTISET(
             SELECT LEVEL
             FROM   DUAL
             WHERE  t.NUM_SHTS > 0
             CONNECT BY LEVEL <= t.NUM_SHTS
           ) AS SYS.ODCINUMBERLIST
         )
       ) n;

Output :

DRAW_NUM             REV        SHT
------------- ---------- ----------
LD-111-639-01          1          1 
LD-111-639-01          1          2 
LD-111-639-01          1          3 
LD-111-639-01          2          1 
LD-111-639-01          2          2 
LD-111-639-01          2          3 
LD-111-639-04          1          1 
LD-111-639-04          1          2