Modify a Table field by adding to it

Question

I have Table1, where I want to modify previous_sum where previous_sum is the sum of the numbers field in Table 2 up to that specific date. Example:

Table1

Date___|___previous_sum
01/01__|___20
01/02__|___50
01/03__|___100

Table2

Date___|___numbers
01/01__|___20
01/02__|___30
01/03__|___50

So, previous_sum is 0 in the beginning but depending on what is in the numbers field up to that date, I want it to add correspondingly to previous_sum.

And what is psql? Is it PostgreSQL or Oracle (PL/SQL)? — Quassnoi
– Quassnoi, Commented Oct 31, 2010 at 22:16

Quassnoi · Accepted Answer · 2010-10-31 22:17:10Z

2

UPDATE  table1
SET     previous_sum = 
        COALESCE(
        (
        SELECT  SUM(numbers)
        FROM    table2
        WHERE   table2.date <= table1.date
        ), 0)

edited Oct 31, 2010 at 22:17

answered Oct 31, 2010 at 22:11

Quassnoi

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Comments

Doggett · Accepted Answer · 2010-10-31 22:15:38Z

0

I'm not quite sure what you're asking, but I think you mean something like this?

UPDATE Table1 SET Previous_Sum = Table2.numbers
FROM Table1
INNER JOIN Table2 ON Table1.Date = Table2.Date

P.S. if you need a SUM just add a group by and SUM the numbers

answered Oct 31, 2010 at 22:15

Doggett

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Comments

George · Accepted Answer · 2010-10-31 22:19:28Z

0

UPDATE Table1 
SET [previous_sum] = (SELECT SUM(numbers) WHERE Table2.Date <= Table1.Date)

edited Oct 31, 2010 at 22:19

answered Oct 31, 2010 at 22:13

George

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