有这种情况，就有table master_balance 存储余额，创建余额的收费金额，然后在 try ，如果出现错误 catch 归还余额：
function charge（）<--调用数据库上的存储函数，其中charge是余额（balance-amount）

PERFORM 1 FROM master_balance where externalkey = $1 and tenant_record_id = $2 for update;

UPDATE master_balance
set balance = balance - $3
where id = (select t.id from master_balance t where t.externalkey = $1 and tenant_record_id = $2 order by id desc limit 1)
returning balance into newbalance;

function return（）<--调用数据库中的存储函数，返回余额（余额+金额）

PERFORM 1 FROM master_balance where externalkey = $1 and tenant_record_id = $2 for update;

UPDATE master_balance
set balance = balance + $3
where id = (select t.id from master_balance t where t.externalkey = $1 and tenant_record_id = $2 order by id desc limit 1)
returning balance into newbalance;

java 语：

try{
balance = charge(12, 1, 4);

//example balance is 5 after charge, and when i print the balance got 5 and the table updated with value 5

Invoice invoice = new Invoice();
invoice.setCurBalance(balance); //balance is 5

tx.commit() <--- error from here
}catch(Exception e)
{
back = return(12, 1, 4); //balance is 6

//try to print back, the value out is 6 but not updated on table
}

但我有这样的情况，收费后的金额，什么时候要抓，是返回正确的值却没有更新表，是抓子句不能做查询吗？