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Re: Question about Oracle compatibility

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: mweilguni(at)sime(dot)com
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Question about Oracle compatibility
Date: 2000-11-27 17:44:46
Message-ID: 11339.975347086@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Mario Weilguni <mweilguni(at)sime(dot)com> writes:
> In Oracle, empty strings and null are basicly the same,

Are you sure about that?  It'd be a pretty major failure to comply with
SQL standard semantics, if so.

SQL92 3.1 (Definitions):

            null value (null): A special value, or mark, that is used to
            indicate the absence of any data value.

SQL92 4.1 (Data types)

         A null value is an implementation-dependent special value that
         is distinct from all non-null values of the associated data type.
         There is effectively only one null value and that value is a member
         of every SQL data type. There is no <literal> for a null value,
         although the keyword NULL is used in some places to indicate that a
         null value is desired.

There is no room there for equating NULL with an empty string.  I also
read the last-quoted sentence to specifically forbid treating the
literal '' as NULL.

			regards, tom lane

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