Setting variables in snowflake - snowflake-cloud-data-platform

Question

I want to define variables before a CTE table and after a CTE table because some variables are dependent on the result of the CTE table. For example
SET(K,B) = (5,2);
with my_data(Key,Index,Value) as (
-- data table as cte
select * from values
(1, 3, 10),
(1, 5, 18),
(1, 14, 4),
(2, 2, 11),
(2, 13, 24),
(2, 29, 40)
)
SELECT VALUE + $K
FROM my_data
This examples works perfectly. But this code:
SET(K,B) = (5,2);
with my_data(Key,Index,Value) as (
-- data table as cte
select * from values
(1, 3, 10 ),
(1, 5, 18 ),
(1, 14, 4 ),
(2, 2, 11 ),
(2, 13, 24),
(2, 29, 40)
)
SET AVG_VAL = (SELECT AVG(VALUE) FROM my_data);
SELECT VALUE + $AVG_VAL
FROM my_data
doesn't because snowflake gives me this error
"SQL compilation error: syntax error line 34 at position 0 unexpected 'SET'."
Should I create a temporary table to store the result of this query (SELECT AVG(VALUE) FROM my_data) in it and then include/use this temporary table for future queries instead of a variable?

Answer 1

Your "CTE" is not a standalone "thing" it only exist in the context of a SELECT.
Thus
WITH cte_x AS (...)
SELECT * FROM cte_x
is one SELECT which has a CTE attached to it.
Thus for you variable assignment the CTE has to be "IN" the paren's
with my_data(Key,Index,Value) as (
select * from values
(1, 3, 10 ),
(1, 5, 18 ),
(1, 14, 4 ),
(2, 2, 11 ),
(2, 13, 24),
(2, 29, 40)
)
SELECT AVG(VALUE) FROM my_data;
AVG(VALUE)
17.833333
given that is a discrete chunk of SQL, that can be captured into the variable:
set AVG_VAL = (
with my_data(Key,Index,Value) as (
select * from values
(1, 3, 10 ),
(1, 5, 18 ),
(1, 14, 4 ),
(2, 2, 11 ),
(2, 13, 24),
(2, 29, 40)
)
SELECT AVG(VALUE) FROM my_data
);
status
Statement executed successfully.
now we can use that value:
select $AVG_VAL * 2;
$AVG_VAL * 2
35.666666
But the next query:
SELECT VALUE + $AVG_VAL
FROM my_data
002003 (42S02): SQL compilation error:
Object 'MY_DATA' does not exist or not authorized.
has no CTE called my_data, so that need to be insert:
with my_data(Key,Index,Value) as (
select * from values
(1, 3, 10 ),
(1, 5, 18 ),
(1, 14, 4 ),
(2, 2, 11 ),
(2, 13, 24),
(2, 29, 40)
)
SELECT VALUE + $AVG_VAL
FROM my_data
If you want a table that can be "used twice" you will need an actual table, at which point I would suggest a temporary table so it only have context in this session.
Which the nature of Pankaj's answer (ether via a permanent or temp table)

Answer 2

This can be done as in -
select * from d2;
+-----+-----+
| ID1 | ID2 |
|-----+-----|
| 1 | 2 |
| 100 | 2 |
| 3 | 4 |
| 300 | 4 |
+-----+-----+
Setting variable -
set (var1) = (select sum(id2) from d2);
+----------------------------------+
| status |
|----------------------------------|
| Statement executed successfully. |
+----------------------------------+
Using variable -
select id1+$var1 from d2;
+-----------+
| ID1+$VAR1 |
|-----------|
| 13 |
| 112 |
| 15 |
| 312 |
+-----------+

Answer 3

An alternatvie approach is to simply use windowed AVG function:
with my_data(Key,Index,Value) as (
-- data table as cte
select * from values
(1, 3, 10),
(1, 5, 18),
(1, 14, 4),
(2, 2, 11),
(2, 13, 24),
(2, 29, 40)
)
SELECT VALUE, AVG(VALUE) OVER(),
VALUE + AVG(VALUE) OVER()
FROM my_data;
Output:
OVER() means that the window used to compute average spans over all rows.