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

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Re^2: Best Perlish way to test if a mysql table exists? by Aristotle (Chancellor) on Jan 31, 2005 at 00:36 UTC
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.	[reply]
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
Re^2: Best Perlish way to test if a mysql table exists? by punch_card_don (Curate) on Jan 31, 2005 at 00:28 UTC
'cause, like I said, there are tens of thousands of tables in the database, and perhaps hundreds of tables in the list - I don't want to bloat this with a lot of extra crunching. The more I think of it, the more a Perl solution that will trap the "table does not exist" error may be best. Forget that fear of gravity, Get a little savagery in your life.	[reply]
Re^3: Best Perlish way to test if a mysql table exists? by trammell (Priest) on Jan 31, 2005 at 02:17 UTC
I don't think it would be a lot of extra crunching. Maybe a single query to list the tables, which you cache in a local hash. Then check the values in the hash to see if the current table you're querying is in the database. Hardly bloated.	[reply]