Whether or not you can insert placeholders for column names is database-specific

Perhaps I misunderstand you. I would be quite surprised if any DBD allowed ordinary placeholders to be used to insert column names.

For maximum clarity, assume I get a dynamic column name and desired value like so: 

my $colname= 'city';
my $value=   'Toledo';

[download]

such that I want to use that to dynamically create the query: 

select * from mytable where city = 'Toledo';

[download]

and I try to use a placeholder for the column name like so: 

my $sth= $dbh->prepare("select * from mytable where ? = ?");
... $sth->execute( $colname, $value );

[download]

Then the query that gets run should surely be: 

select * from mytable where 'city' = 'Toledo';

[download]

which should always return 0 rows since the string 'city' is never equal to the string 'Toledo'.

But the link you provide is indeed an excellent resource for this type of question. Thanks!

- tye        

In reply to Re^2: DBI, place holders and CGI forms (column names) by tye
in thread DBI, place holders and CGI forms by Anonymous Monk

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