(dkubb) Re: (3) A more elegant solution?

IIRC, the DBI spec doesn't support using placeholders for the column names, only values. Programming the Perl DBI, p 221 says the following:

With most drivers, placeholders can't be used for any element of a statement that would prevent the database server from validating the statement and creating a query execution plan for it. For example:
"SELECT name, age FROM ?"       #wrong (will probably fail)
"SELECT name, ?   FROM people"  #wrong (but may not 'fail')
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While this may not fail with some databases like MySQL, it *may* fail on databases like Oracle that natively support placeholders. (can anyone confirm this?)

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Re: (dkubb) Re: (3) A more elegant solution? by da (Friar) on Jun 06, 2001 at 21:43 UTC
Here's what happens under oracle: `# fails under oracle my $sth = $dbh->prepare("select name, age from ?") # does not fail under oracle, but gives wrong results. my $sth = $dbh->prepare("select name, ? from table") # outputs n copies of the string "age", for n rows in table. $sth->execute("age")` [download] `___` `-DA`	[reply] [d/l] [select]

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Re: (dkubb) Re: (3) A more elegant solution?
by da (Friar) on Jun 06, 2001 at 21:43 UTC

# fails under oracle
my $sth = $dbh->prepare("select name, age from ?")     

# does not fail under oracle, but gives wrong results.
my $sth = $dbh->prepare("select name, ? from table")  

# outputs n copies of the string "age", for n rows in table.
$sth->execute("age")
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-DA

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