General Bug Report: empty SELECT WHEREs return error

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POSTGRESQL BUG REPORT TEMPLATE
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Your name : Austin Schutz
Your email address : tex(at)habit(dot)com

Category : runtime: back-end: SQL
Severity : serious

Summary: empty SELECT WHEREs return error

System Configuration
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Operating System : SunOS 5.6

PostgreSQL version : 6.0

Compiler used : gcc 2.8.1

Hardware:
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SunOS pita 5.6 Generic_105181-09 sun4u sparc SUNW,Ultra-1

Versions of other tools:
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Problem Description:
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select * from foo where bar = "baz"
produces "ERROR: attribute 'hna' not found"
if there is no row with bar == "baz".
Rather than errorring an empty set should be returned.
This is important for cross-db-portable applications
which need to know whether a legitimate query returns
no rows vs. a 'bad' query.
It would be possible to test the error response for
being the specific 'attribute not found' error, but this is
extremely un-portable behavior (code would only work on
postgres) and further would mask cases where column bar
doesn't exist and the 'attribute not found' error is
correct.

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Test Case:
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create table foo (bar char(1));
select * from foo where ( bar = "baz" );
ERROR: attribute 'baz' not found

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Solution:
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