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POProblems with parameterizing timestamp references in PostgreSQL in Perl
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2013-10-17T18:23:28.413
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2013-10-17T20:55:38.217
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I am trying to use a parameterized query in a Perl script to get some timestamps back from a Postgres database. Here's a cut-and-dried example, solely for pedagogical purposes. I've defined <code>$start_date</code> and <code>$end_date</code> as timestamps and intervals: <pre><code>my $start_date = "current_timestamp - interval '6 hours'"; my $end_date = "current_timestamp"; </code></pre> I use the following to submit to the database, with <code>$dbh</code> defined earlier: <pre><code>my $sql = "SELECT cast(? as timestamp), cast(? as timestamp)"; my $sth = $dbh->prepare($sql); $sth->execute($start_date, $end_date); </code></pre> When I do this, I get a somewhat confusing error. <pre><code>DBD::Pg::st execute failed: ERROR: date/time value "current" is no longer supported </code></pre> I understand that <code>current</code> hasn't been supported in PG since 7.2, but I'm not using that. I'm using <code>current_timestamp</code>, which is supported, AFACT. To wit, if I enter into <code>psql</code>: <pre><code>select (cast(current_timestamp - interval '6 hours' as timestamp), cast(current_timestamp as timestamp)); </code></pre> the result is what I expect (two timestamps, the former six hours previous to the latter). I could also use <code>now()</code> rather than <code>current_timestamp</code>. I can use it in the following way: <pre><code>my $start_date = "now() - interval '6 hours'"; my $end_date = "now()"; </code></pre> When I try to run the query in perl, I get the following error: <pre><code>DBD::Pg::st execute failed: ERROR: invalid input syntax for type timestamp: "now() - interval '6 hours'" </code></pre> Yet, the query: <pre><code>select (cast(now() - interval '6 hours' as timestamp), cast(now() as timestamp)); </code></pre> gives me the expected result. I am quite flummoxed.
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<sql><perl><postgresql>
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Problems with parameterizing timestamp references in PostgreSQL in Perl
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