SQL - Update Rows from a list of values - sql

Question

So Table Setup is:
Column1 Column2 Column3
A 1 Null
B 2 Null
C 1 Null
D 2 Null
E 1 Null
F 2 Null
G 1 Null
H 2 Null
I would like to update Column3 with an array of values (Value1, Value2, Value3) and cycle through that list until the update is complete
The ultimate goal is for the table to look like this:
Column1 Column2 Column3
A 1 Value1
B 2 Value2
C 1 Value3
D 2 Value1
E 1 Value2
F 2 Value3
G 1 Value1
H 2 Value2
I originally tried in powershell but it was not working as I would have liked because of how the data is being imported, so now I am looking towards SQL. Any suggestions would be great!

Answer 1

You could try an update join here. The approach below is to assign an ordered sequence to both your original table and the "array" of values for updating. We join using modulus logic, such that your table's sequence ordering will match up the values in the array and will wrap around until all values have been assigned.
WITH cte AS (
SELECT *, ROW_NUMBER() OVER (ORDER BY Column1) rn
FROM yourTable
)
UPDATE t1
SET Column3 = t2.val
FROM cte t1
INNER JOIN
(
SELECT 1 AS id, 'Value1' AS val UNION ALL
SELECT 2, 'Value2' UNION ALL
SELECT 3, 'Value3'
) t2
ON t2.id = 1 + ((t1.rn - 1) % 3);
Demo

Answer 2

Assuming you can put the "array" in a table, you can use something like this:
with vals as (
select v.*,
row_number() over (order by (select null)) - 1 as seqnum,
count(*) over () as cnt
from (values ('Value1'), ('Value2'), ('Value3')) v(val)
)
update t
set t.column3 = v.val
from (select t.*,
row_number() over (order by column1) - 1 as seqnum
from t
) t join
vals v
on t.seqnum % v.cnt = v.seqnum;
The basic idea is to enumerate the rows in each table and then use modulo arithmetic to match them.