单张桌子上的两个连接

使用表别名

select t1.id, t2a.dispval as acc, t2b.dispval as offacc, t1.debit, t1.credit
from   Table1 as t1
       inner join Table2 as t2a on t2a.id = t1.acc
       inner join Table2 as t2b on t2b.id = t1.offacc

考虑在表1上使用左联接两次,如下所示

select 
t1.id,
acc=t2.dispval,
offacc=t3.dispval,
t1.debit,
t1.credit
from Table1 t1 left join
     Table2 t2 on t1.acc=t2.id
     Table2 t3 on t1.offacc=t3.id

加入的备选方案:

select id,
       (select dispval from Table2 where id = [t1].acc) as acc,
       (select dispval from Table2 where id = [t1].offacc) as offacc,
       debit,
       credit
from Table1 [t1]