使用 JOIN 但我无法量化绩效收益：

SELECT ew.emp_address
FROM emp_leave_wallet ew
LEFT OUTER JOIN transaction t on
    t.emp_address = ew.emp_address
WHERE ew.attached = "mycompany_wallet" and
      t.emp_address IS NULL

使用 not exists :

select ew.emp_addres
from emp_leave_wallet ew
where ew.attached = "mycompany_wallet" and
      not exists (select 1 from transaction t where t.destination_address = ew.emp_address);

我会从 not exists :

select lw.emp_address
from emp_leave_wallet lw
where lw.attached  = 'mycompany_wallet' and
      not exists (select 1
                  from destination_address da
                  where lw.emp_address = da.destination_address 
                 );

那么对于这个查询，您肯定需要一个索引 destination_address(destination_address) 可能是在 (attached, emp_address) .

select emp_address
from emp_leave_wallet
where attached  ="mycompany_wallet" and
      emp_address not in (select destination_address from transaction);

你的 emp_leave_wallet 以及 transaction 表应该有id字段（我猜。。。 emp_id , transaction_id )
如果是我我会。。。

select emp_address
from emp_leave_wallet elw
inner join transaction t
on elw.emp_id = t.transacation_id

使用 NOT EXISTS 如果中没有匹配的行，则返回记录 transaction 表基于 where 条件：

select emp_address
from emp_leave_wallet e
where attached = 'mycompany_wallter'
  and not exists (
    select 1
    from transaction t
    where e.emp_address = t.destination_address
    )

创建索引：

CREATE INDEX idx1 ON emp_leave_wallet(attached, emp_address);
CREATE INDEX idx2 ON transaction(destination_address);