"=?ISO-8859-1?B?WGlvbmcgSGU=?=" <iihero(at)qq(dot)com> writes:
> mydb=# create table test1(id1 int primary key, col2 varchar(32));
> mydb=# create table test2(id2 int primary key, col2 varchar(32));
> mydb=# select * from test1 where id1 in (select id1 from test2 where id2 = 2);
> In the above query: id1 is not a column of table test2.
Nope, but it's a legal outer reference.
> Should not we expect this should be en error instead of it thinking it's a column from the table : test1?
This behavior is required by the SQL standard, and has been for
decades. Yes, it trips up novices all the time, but it does
have valid use-cases.
regards, tom lane