将同一组中的每个列值移动到新列 SQL Big Query

Question

I have faced an issue when trying to transpose rows to columns.

My table looks like this:

And the result table should look like this:

I tried to solve this problem with PIVOT() but then I realized this is not the case. Can anyone help me with that?

Edit 1: the number of names is not infinite (4 at most).

Edit 2: I've realized I've lost all the rows when there is NULL in name column.

I know I could do it with UNION, but is there more elegant solution to this problem?

Desired result would then be:

Answer 1

Consider below option

select * from (
  select *
  from your_table, 
  unnest(split(name, ', ')) word with offset
)
pivot (min(word) as name for offset + 1 in (1, 2, 3))   

if applied to sample data in your question

with your_table as (
  select 'x1' id, 'yellow' name union all
  select 'x2', 'orange' union all
  select 'x3', 'pink, blue' union all
  select 'x4', 'pink, blue, yellow' 
)    

output is

Answer 2

It depends on how many names you want to split into new columns. With the data that you, shared you can try this query below:

SELECT DISTINCT t1.id, t1.name,
split(t1.name, ', ')[SAFE_offset(0)] as name_1,
split(t1.name, ', ')[SAFE_offset(1)] as name_2,
split(t1.name, ', ')[SAFE_offset(2)] as name_3
from `dataset.table` as t1

This brings the below output:

I use SAFE_OFFSET because if you only use OFFSET the id 1,2,3 wouldn't allow it because they bring nulls.

Answer 3

How can I keep the rows when there is NULL in name column? I appreciate you help!

Consider below

select * from (
  select *
  from your_table
  left join unnest(split(name, ', ')) word with offset
)
pivot (min(word) as name for offset + 1 in (1, 2, 3))        

if applied to sample data in your question

with your_table as (
  select 'x1' id, 'yellow' name union all
  select 'x2', 'orange' union all
  select 'x3', 'pink, blue' union all
  select 'x4', 'pink, blue, yellow' union all 
  select 'x5', null union all
  select 'x6', null 
)              

the output is