Re: Syntax question: use of join/using with fully qualified table name - Mailing list pgsql-sql

Bryce Nesbitt escribió:
> I've got a join where a certain column name appears twice:
> 
> select username,last_name from eg_member join eg_membership using
> (member_id) join eg_account using (account_id) join eg_person using
> (person_id);
> ERROR:  common column name "person_id" appears more than once in left table
> 
> 
> My first inclination was to fully quality the table name.  Why would
> this not be acceptable syntax?
> 
> select username,last_name from eg_member join eg_membership using
> (member_id) join eg_account using (account_id) join eg_person using
> (eg_member.person_id);
> ERROR:  syntax error at or near "." at character 145

Did you read the manual?

USING (join_column [, ...])
    A clause of the form USING ( a, b, ... ) is shorthand for ON 
left_table.a = right_table.a AND left_table.b = right_table.b .... Also, 
USING implies that only one of each pair of equivalent columns will be 
included in the join output, not both.