计算在MySQL运行平衡，观点

Question

我简单的表名为ass_material与此列：

mat_id mat_name supplier request stock_received date 
1   alloy  test  30   0    feb13 
2   alloy  test  30   10   feb14 
3   alloy  test  30   20   feb14 

我怎样才能产生，或计算出它作为： 它也将产生一个“完整”的状态时stock_balance和要求火柴。

mat_id mat_name supplier request stock_received Stock_balance date status 
    1   alloy  test  30   0     0  feb13 
    2   alloy  test  30   10    10  feb14 
    3   alloy  test  30   20    30  feb14 complete 

这里是我的引用代码从我的另一种观点： 我如何可以调整到我所期望的输出这上面？

SELECT m.`mat_id`, m.`mat_name`, m.`request`, m.`stock_receieved`, 
     (select sum(stock_received) - sum(stock_received) 
     from material m2 
     where m2.mat_name = m.mat_name and 
       m2.mat_id <= m.mat_id 
     ) as Stock_balance, 
     m.`date`, 
     s.`sup_name` 
FROM `material` m 
LEFT JOIN `supplier` s on s.sup_id = m.supplier_id 
ORDER BY m.`mat_id` ASC; 

Answer 1

如果stock_balance只是stock_received总和，然后使用子查询：

SELECT m.`mat_id`, m.`mat_name`, m.`request`, m.`stock_receieved`, 
     (select sum(stock_received) 
     from material m2 
     where m2.mat_name = m.mat_name and 
       m2.mat_id <= m.mat_id 
     ) as Stock_balance, 
     (case when (select sum(stock_received) 
        from material m2 
        where m2.mat_name = m.mat_name and 
         m2.mat_id <= m.mat_id 
       ) = request 
      then 'Complete' 
      else 'Incomplete' 
     end) as status, 
     m.`date`, 
     s.`sup_name` 
FROM `material` m LEFT JOIN 
    `supplier` s 
    on s.sup_id = m.supplier_id 
ORDER BY m.`mat_id` ASC;