如何将值从一列分隔为2列作为表

Question

Journal_T - Basically this is the journal table with positive and negative values. Fields are: id, date, ref, description, amount, segment, period, year.

I want to display this in two separate columns - debits (containing positive values) and credits (containing negative values). Following is the query I am using:

$qry = mysql_query("SELECT id, date, ref, description, SUM(amount), 
                           segment, period, year
                      FROM Journal_T 
                  GROUP BY segment, year, period, id") or die(mysql_error());

Answer 1

If I understand the schema, do it with a CASE:

SELECT id,
  date,
  ref,
  description,
  CASE WHEN SUM(amount) >= 0 THEN SUM(amount) ELSE NULL END AS positive,
  CASE WHEN SUM(amount) < 0 THEN SUM(amount) ELSE NULL END AS negative,
 ,segment,period,year FROM Journal_T GROUP BY segment,year,period,id