Inserting multiple formulas into columns sql

I have a question about inserting multiple formulas into a data table, using sql.

I have a large data table, table g. Some columns of g are

    id1       id2      xyz
******************************
    123       456       4
    123       123       1
    789       456       5
    456       123       2
    123       789       4

I have created another table, placeholder, using these commands

CREATE TABLE placeholder(id, count, sum_1, sum_2)

Next, I am trying to insert data into placeholder and am running into an issue.

The variable 'id' in 'placeholder' can match one can match neither, one, or two of id1 id2. I have the count variable coded correctly, but I am struggling with a formula to insert data into sum_1 and sum_2.

sum_1 needs to be a sum of xyz, grouped by id1

sum_2 needs to be a sum of xyz, grouped by id2

I am trying to insert the data into placeholder using this code

INSERT INTO placeholder 
SELECT 
id1, 
COUNT(*) AS 'num' FROM g GROUP BY id1, 
SUM(xyz) AS 'num' FROM g GROUP BY id1,
SUM(xyz) AS 'num' FROM g GROUP BY id2

The first two lines work but the last two lines (beginnign with SUM) are not working. I keep getting the error OperationalError: near "SELECT": syntax error .

How do I calculate the conditional sums and insert them into my table?