PostgreSQL crosstab transpose row to column - sql

Question

Hi guys im trying to transpose a row query result to 1 row per columns
1st query is select * from sku;
the result is :
id sku sku_code travel_code
1 sku1 1 1
2 sku1 2 2
3 sku1 3 3
4 sku1 4 4
5 sku1 5 5
6 sku1 6 6
7 sku1 7 7
8 sku2 8 8
9 sku2 9 9
10 sku2 10 10
11 sku2 11 11
12 sku2 12 12
13 sku2 13 13
14 sku2 14 14
15 sku3 15 15
16 sku3 16 16
17 sku3 17 17
18 sku3 18 18
19 sku3 19 19
20 sku3 20 21
21 sku3 21 21
expected output is
SKU SKU_CODE TRAVEL_CODE
sku1 1 2 3 4 5 6 7 1 2 3 4 5 6 7
sku2 8 9 10 11 12 13 14 8 9 10 11 12 13 14
sku3 15 16 17 18 19 20 21 15 16 17 18 19 20 21
no header is ok

Answer 1

You can use grouping with min and max aggregation functions
with tab(sku, sku_cod, travel_code) as
(
select 'sku1',109,'01' union all
select 'sku2',209,'02' union all
select 'sku2',309,'03' union all
select 'sku1',409,'04'
)
select sku, min(sku_cod) as sku_cod1, max(sku_cod) as sku_cod2,
min(travel_code) as travel_code1, max(travel_code) as travel_code2
from tab
group by sku
order by sku;
sku sku_cod1 sku_cod2 travel_code1 travel_code2
sku1 109 409 01 04
sku2 209 309 02 03

Answer 2

You are using Postgres, so I would recommend storing the values as arrays:
select sku, array_agg(sku_cod) as sku_cods
array_agg(travel_code) as travel_codes
from t
group by sku
order by sku;
This will allow you to handle more than two values.