Postgres 12

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create table survey (formula text, var1 int,  var2 int, var3 int);

insert into survey
values
('var1 + var2', 12, 9, 2),
('var3 * (var1 * var2)', 20, 10, 1);

2 rows affected

CREATE or replace FUNCTION cpt_scores(p_row survey) 
  RETURNS int
AS
$$
DECLARE
  score   numeric;
  in_rec  record;
  l_sql text;
BEGIN
  l_sql := format('SELECT %s FROM (values (%s, %s, %s)) AS t(var1, var2, var3)', 
                   p_row.formula, p_row.var1, p_row.var2, p_row.var3);
  execute l_sql INTO score;
  return score;
END;  
$$ 
language plpgsql;

select s.*, cpt_scores(s) as score
from survey s;



formula
var1
var2
var3
score


var1 + var2
12
9
2
21

var3 * (var1 * var2)
20
10
1
200