Nota:esta respuesta se aplica a la pregunta original.
Sentencia SQL con anotaciones:
select a.name -- 'a' is undefined
, ird_num -- note: always qualify (helps others read it)
, loan_num -- same
, contract_date -- same
from a2_loan -- is this support to have alias 'a'?
, customer b -- not table `a2_customer`
, customer c -- not table `a2_customer`
where aname=b.ird_num -- missing period(?), and 'a' is undefined
and b name=c.name -- missing period
