我正在使用sqlite3数据库，我试图从两个交叉连接的表中获取数据。它们有一些外键，我无法获得货币名称的参考值（b_currency和s_currency）。
他们需要像“美元”，“欧元”，“TRL”等。
SQL语句：

select 
a.pid, 
person.fullname,
a.amount as b_amount,
b.amount as s_amount,
a.currency as b_currency,
b.currency as s_currency,
a.rate as b_rate,
b.rate as s_rate,
`user`.username,
a.`date`
from buy_process as a
inner join person
on a.fullname=person.id
inner join  currency
on  b_currency=currency.id and s_currency=currency.id
inner join  `user` 
on a.`user`=`user`.id
cross join sell_process as b
where a.pid=b.pid;

Buy_Process和Sell_Process表字段相同：

-- Describe BUY_PROCESS
CREATE TABLE `buy_process`(
    id integer primary key AUTOINCREMENT,
    pid VARCHAR(50) NOT NULL UNIQUE,
    fullname INTEGER NOT NULL,
    amount VARCHAR(50) NOT NULL,
    currency INTEGER NOT NULL,
    rate VARCHAR(50) NOT NULL,
    `user` INTEGER NOT NULL,
    `date` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    CONSTRAINT fkbuy_fullname FOREIGN KEY(fullname) REFERENCES person(id),
    CONSTRAINT fkbuy_currency FOREIGN KEY(currency) REFERENCES currency(id),
    CONSTRAINT fkbuy_user FOREIGN KEY(`user`) REFERENCES `user`(id)
);

结果：
Result image
我尝试更改字段名称，但未成功：

a.pid, 
person.fullname,
a.amount as b_amount,
b.amount,
currency.name as b_currency,
currency.name as s_currency,
a.rate as b_rate,
b.rate as s_rate,
`user`.username,
a.`date`
from buy_process as a
inner join person
on a.fullname=person.id
inner join  currency
on  b_currency=currency.id and s_currency=currency.id
inner join  `user` 
on a.`user`=`user`.id
cross join sell_process as b
where a.pid=b.pid;