Question

I have a normalized table (table a) and a non-normalized table (table b), like this:

Basically, for each row in table a for the same student ID, I want to read all the parents with the same studentId and put the data into one row in table B.

So if I have 3 rows in table A, then there would be one row in table B with 3 of the 4 parent fields filled in. Any help for an SQl query for this would be appreciated.

Sample for data in table A

parentID studentID parentName
1         1         test
2         1          test1

Result I want in table B

studentID parent1 parent2
1         test    test1

Answer 1

Here’s a query that would generate the flat results you are looking for. Is there a reason you couldn’t just make this a view instead of permanently restructuring your data?

with RankedNormalizedFamily as (
  select
    ROW_NUMBER() over (PARTITION by studentid ORDER BY parentid) as rank
    ,parentID
    ,studentID
    ,parentName
  from
    NormalizedFamily
)
select
  studentID
  ,max(case when rank = 1 then parentName end) as parentName1
  ,max(case when rank = 2 then parentName end) as parentName2
  ,max(case when rank = 3 then parentName end) as parentName3
  ,max(case when rank = 4 then parentName end) as parentName4
from
  RankedNormalizedFamily f
group by
  studentID

Demo: http://www.sqlfiddle.com/#!3/91843/9

To push this data into FlatFamily you would use an INSERT...SELECT:

insert into FlatFamily
select
  studentID
  ...