How to bind horizontal values of a table to a vertical values of another table in oracle database - oracle

Question

i have 2 tables .
The columns start with attributes are change based on department. the description of attributes are here
My requirement is to get the values of each attributes with its primary key based on the department as table bellow.
Honestly i am stuck on this problem in my program. I have no permission to change the tables and there is no common unique key column.i would appreciate if anyone could provide me a suggestion.

Answer 1

with a as (
select a.*, row_number() over (partition by department order by attributeID) rn
from attributes a),
e as (
select employeeId, department, attribute1, 1 rn from employees union all
select employeeId, department, attribute2, 2 rn from employees union all
select employeeId, department, attribute3, 3 rn from employees
)
select e.employeeId, a.attributeid, e.department, a.attribute, a.meaning,
e.attribute1 as value
from e join a on a.department=e.department and a.rn=e.rn
order by e.employeeId, a.attributeid
Test data and output:
create table employees (employeeID number(3), name varchar2(10), department varchar2(5), age number(3), attribute1 varchar2(10), attribute2 varchar2(10), attribute3 varchar2(10));
insert into employees values (1, 'john', 'IT', 22, 'attr1val1', 'attr2val2', null);
insert into employees values (2, 'jane', 'HR', 32, 'attr1val3', 'attr2val4', 'attr3val5');
insert into employees values (3, 'joe', 'HR', 23, 'attr1val6', 'attr2val7', 'attr3val8');
insert into employees values (4, 'jack', 'IT', 45, 'attr1val9', 'attr2val10', null);
create table attributes (attributeID number(3), department varchar2(10), attribute varchar2(10), meaning varchar2(10));
insert into attributes values (1, 'IT', 'attribute1', 'laptoptype');
insert into attributes values (2, 'IT', 'attribute2', 'networkloc');
insert into attributes values (3, 'HR', 'attribute1', 'location');
insert into attributes values (4, 'HR', 'attribute2', 'position');
insert into attributes values (5, 'HR', 'attribute3', 'allocation');
EMPLOYEEID ATTRIBUTEID DEPARTMENT ATTRIBUTE MEANING VALUE
---------- ----------- ---------- ---------- ---------- ----------
1 1 IT attribute1 laptoptype attr1val1
1 2 IT attribute2 networkloc attr2val2
2 3 HR attribute1 location attr1val3
2 4 HR attribute2 position attr2val4
2 5 HR attribute3 allocation attr3val5
3 3 HR attribute1 location attr1val6
3 4 HR attribute2 position attr2val7
3 5 HR attribute3 allocation attr3val8
4 1 IT attribute1 laptoptype attr1val9
4 2 IT attribute2 networkloc attr2val10
Edit: Explanation
In answer I used with
clause just to divide solution into readable steps. You can move them into from clause of main query if it is
more comfortable for you. Anyway: subquery a reads data from table attributes and adds number for rows,
so for each department they are allways numbered from 1. I used row_number() for that. Subquery e unions (all) required attributes and numbers
them accordingly. Numbers generated in both subqueries are then used in main join: a.department=e.department and a.rn=e.rn.
Alternative 1 - if you are using Oracle 11g you could use the unpivot. See what is generated by subquery, and how it is joined with attributes table:
with e as (
select employeeId, name, department, attribute, value from employees
unpivot (value for attribute in ("ATTRIBUTE1", "ATTRIBUTE2", "ATTRIBUTE3"))
)
select e.employeeId, a.attributeid, e.department, a.attribute,
a.meaning, e.value
from e join attributes a on a.department=e.department
and lower(a.attribute)=lower(e.attribute)
order by e.employeeId, a.attributeid;
Alternative 2 - with hierarchical subquery generator (subquery r), realised by connect by which simple creates numbers from 1, 2, 3 which are next joined with employees and proper attribute
is attached as value in case clause. Rest is made in similiar way like in original answer.
with a as (
select a.*, row_number() over (partition by department order by attributeID) rn
from attributes a),
r as (select level rn from dual connect by level<=3),
e as (
select employeeId, department, rn,
case when r.rn = 1 then attribute1
when r.rn = 2 then attribute2
when r.rn = 3 then attribute3
end value
from employees cross join r
)
select e.employeeId, a.attributeid, e.department, a.attribute,
a.meaning, e.value
from e join a on a.department=e.department and a.rn=e.rn
order by e.employeeId, a.attributeid
All three versions gave me the same output. I also tested first option on similiar table with 100k rows and get output in few seconds (for 5 attributes). Please test all solutions and try to understand them. If you can use unpivot version I would prefer this.
Sorry for delayed explanation and any language mistakes.

Answer 2

The WITH clause was added with Oracle 9.2 and should do the trick. For the other attributes just add more sub queries where the filter is att.attribute = 'attribute2' or 'Attribute3'...
WITH e AS
(SELECT emp.employee_ID, emp.department, emp.attribute1
FROM employee emp),
a AS (SELECT att.attribute_id, att.attribute, att.meaning
FROM attribute_TYPE att
WHERE att.attribute = 'attribute1')a
SELECT e.employeeid, att.attributeid, e.department, a.attribute,
a.meaning e.attribute1
FROM e JOIN a ON e.department = a.department