PostgreSQL 实现累加
exchange=# select invoice_id, client_id , total_amount,invoice_end frominvoice order by invoice_id ; invoice_id | client_id | total_amount | invoice_end ------------+-----------+--------------+------------------------ 31 | 1 | 14.06202 | 2010-12-20 00:00:00+00 71 | 4 | -45.25617 | 2010-12-20 00:00:00+00 75 | 3 | 2.52500 | 2010-12-17 00:00:00+00 76 | 3 | 9.36850 | 2010-12-18 00:00:00+00 77 | 3 | 34.40367 | 2010-12-19 00:00:00+00 78 | 3 | 0.00000 | 2010-12-20 00:00:00+00(6 rows)exchange=#现在将 total_amount累加
exchange=# select invoice.invoice_id, invoice.client_id ,invoice. total_amount,invoice.invoice_end, (select sum(total_amount) as past_due from invoice as inner_invoice where client_id = invoice.client_id and inner_invoice.invoice_end <= invoice.invoice_end) as grand_total from invoiceorderby invoice.invoice_id; invoice_id | client_id | total_amount | invoice_end | grand_total ------------+-----------+--------------+------------------------+------------- 31 | 1 | 14.06202 | 2010-12-20 00:00:00+00 | 14.06202 71 | 4 | -45.25617 | 2010-12-20 00:00:00+00 | -45.25617 75 | 3 | 2.52500 | 2010-12-17 00:00:00+00 | 2.52500 76 | 3 | 9.36850 | 2010-12-18 00:00:00+00 | 11.89350 77 | 3 | 34.40367 | 2010-12-19 00:00:00+00 | 46.29717 78 | 3 | 0.00000 | 2010-12-20 00:00:00+00 | 46.29717(6 rows)exchange=#
grand_total为累加的字段
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