How do I calculate a running SUM on a SQLite query?

Question

How do I get a column that is the sum of all the values before of another column?

Answer 1

If you have a version of SQLite that doesn't support OVER here is another approach using recursion against a group_concat string of rows.
On SQLite version 3.22.0 2018-01-22 18:45:57 group_concat returns rows in database order. Create a common table expression and order it for different orders as in table work1 in the example.

/* cumulative running total using group_concat and recursion
   adapted from https://blog.expensify.com/2015/09/25/the-simplest-sqlite-common-table-expression-tutorial/
*/

WITH RECURSIVE work2 AS (
  SELECT NULL AS name, NULL AS gdppc, 0 AS cum, (select group_concat(name) from work1) AS gcname, (select group_concat(gdppc) from work1) AS gcgdppc 
  UNION
        SELECT
            CASE
                WHEN INSTR(gcname, ',' )>0 THEN 
                    SUBSTR(gcname, 0, INSTR(gcname,','))
                ELSE
                    gcname
            END,
            CASE
                WHEN INSTR(gcgdppc, ',' )>0 THEN 
                    SUBSTR(gcgdppc, 0, INSTR(gcgdppc,','))
                ELSE
                    gcgdppc
            END,
            CASE
                WHEN INSTR(gcgdppc, ',' )>0 THEN 
                    cum + SUBSTR(gcgdppc, 0, INSTR(gcgdppc,','))
                ELSE
                    cum + gcgdppc
            END,
            CASE
                WHEN INSTR( gcname, ',' )>0 THEN 
                    SUBSTR( gcname, INSTR( gcname, ',' )+1 )
                ELSE
                    NULL
            END,
            CASE
                WHEN INSTR(gcgdppc, ',' )>0 THEN 
                    SUBSTR( gcgdppc, INSTR( gcgdppc, ',' )+1 )
                ELSE
                    NULL
            END
        FROM work2
        WHERE gcgdppc IS NOT NULL

  ), 
/* SQLite version 3.22.0 2018-01-22 18:45:57
   group_concat ignores ORDER BY when specified against the base table
   but does appear to follow the order of a common table expression 
*/
  work1 AS (select * from gdppc order by gdppc),

  gdppc AS (SELECT 'Burundi' AS name,399.657 AS gdppc
            UNION
            SELECT 'Democratic Republic of Congo', 329.645
            UNION
            SELECT 'Liberia',385.417
            UNION
            SELECT 'Zimbabwe',370.465)

select name,gdppc,cum from work2 where name IS NOT NULL;
/* result
Democratic Republic of Congo|329.645|329.645
Zimbabwe|370.465|700.11
Liberia|385.417|1085.527
Burundi|399.657|1485.184
*/