将期初余额添加到MySQL中的第一个结束余额行

Question

我有一个MySQL表，在表中显示借方、贷方和余额。我已将以下定义、示例数据和代码加载到SQL Fiddle中

CREATE TABLE chequebook (
  entry_date timestamp default now() PRIMARY KEY,
  entry_item varchar(48) NOT NULL DEFAULT '',
  entry_amount decimal(10,2) NOT NULL DEFAULT 0.00
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO chequebook (entry_date,entry_item,entry_amount) VALUES 
('2010-01-02 12:34:00','Deposit A',215.56),
('2010-01-02 21:44:00','Withdrawal A' ,-23.34),
('2010-01-03 10:44:00','Withdrawal B',-150.15),
('2010-01-03 15:44:00','Deposit B',154.67),
('2010-01-04 18:44:00','Withdrawal C',-65.09),
('2010-01-05 08:44:00','Withdrawal D',-74.23),
('2010-01-06 14:44:00','Deposit C',325.12),
('2010-01-06 20:44:00','Withdrawal E',-80.12),
('2010-01-07 04:44:00','Withdrawal F',-110.34),
('2010-01-07 16:44:00','Withdrawal G',-150.25),
('2010-01-08 16:44:00','Withdrawal H',-23.90),
('2010-01-08 21:44:00','Withdrawal I',-75.66),
('2010-01-08 22:44:00','Deposit C',275.78),
('2010-01-09 11:44:00','Withdrawal K',-85.99),
('2010-01-09 21:44:00','Withdrawal J',-100.00); 

set @depos=0;
set @total=0;
select 
  entry_date, 
  entry_item, 
  entry_amount, 
  if( entry_amount>0, @depos:=entry_amount, @depos:=@depos+entry_amount ) as depos_bal,
  @total:=@total+entry_amount as net_bal
from chequebook
order by entry_date; 

当我想从PHP查询中向net_bal列添加一个开放余额时，我将面临一些问题。

我面临的问题是，在第一栏中添加期初余额，在第一栏之后，应该从所需字段中减去或加上。

例如：

|                entry_date |   entry_item | entry_amount | depos_bal | net_bal |
|---------------------------|--------------|--------------|-----------|---------|
| January, 02 2010 12:34:00 |    Deposit A |       215.56 |   5215.56 | 5215.56 | <--- 5000 is openingbalance
| January, 02 2010 21:44:00 | Withdrawal A |       -23.34 |   5192.22 | 5192.22 |
| January, 03 2010 10:44:00 | Withdrawal B |      -150.15 |   5042.07 | 5042.07 |

开口平衡是从不同的桌子上取来的。

我怎么能完成这件事？

Answer 1

您可以将初始局部变量@Total变量设置为初始余额。来自您的SQLFiddle：

set @depos=0;
set @total=5000;
select 
  entry_date, 
  entry_item, 
  entry_amount, 
  if( entry_amount>0, @depos:=entry_amount, @depos:=@depos+entry_amount ) as depos_bal,
  @total:=@total+entry_amount as net_bal from chequebook
order by entry_date; 

如果它来自不同的查询，请按此方式设置变量。