Re^2: Best Perlish way to test if a mysql table exists?

eval is only necessary if DBI's RaiseError flag was set on connection to the database; otherwise $dbh->err must be checked. This should probably be done with a query such as SELECT 1 FROM table WHERE 0 which would always succeed but would never return any results, provided the table exists.

Makeshifts last the longest.

Comment on Re^2: Best Perlish way to test if a mysql table exists?

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Re^3: Best Perlish way to test if a mysql table exists? by punch_card_don (Curate) on Jan 31, 2005 at 01:14 UTC
Just read up on RaiseError - maybe a possibility. But that would create an error trapping nightmare for me having to re-write trappig code for every line of sql in the script.... Oh, for a "if table exists" function! Forget that fear of gravity, Get a little savagery in your life.	[reply]
Re^4: Best Perlish way to test if a mysql table exists? by Aristotle (Chancellor) on Jan 31, 2005 at 02:25 UTC
To be honest, I don't think such functionality is particularly warranted. Constantly checking for the existence of a table smacks of bad design. Sometimes we are stuck with bad design, of course. Makeshifts last the longest.	[reply]
Re^4: Best Perlish way to test if a mysql table exists? by blokhead (Monsignor) on Jan 31, 2005 at 05:35 UTC
re-write trappig code for every line of sql in the script.... Not necessary, you can set RaiseError for just that particular query. BTW, did you know you can localize hash/array values? Even if the hash/array is a lexical variable? `eval { local $DBH->{RaiseError} = 1; local $DBH->{PrintError} = 0; $sth = $DBH->prepare($sql); $sth->execute; 1; }; # table was found if $@ is empty` [download] Alternately, you can just set RaiseError/PrintError on the individual statement handle (not the database connection handle). blokhead	[reply] [d/l]
Re^5: Best Perlish way to test if a mysql table exists? by Aristotle (Chancellor) on Jan 31, 2005 at 06:24 UTC
Except it wasn't the point to set that for a single query. It's usually best to set RaiseError on the connection handle and wrap larger blocks of calls with an eval; that frees you from the responsibility of constantly checking `$dbh->err`. If you aren't already using RaiseError, I don't see how going through all the trouble to enable it for one query is better than the regular `$dbh->err` check. Makeshifts last the longest.	[reply]