Hello dbi-users,
I am reading perldoc DBI,
and there is a section there that describes how to handle
placeholders in WHERE clauses on columns that can contain NULL.
That section has a table listing which database brands support which clause
styles.
That table did not contain entries for (my favorite) MySQL
(i did not check whether i had very latest version of that perldoc,
just installed it from Debian unstable).
So i downloaded script referred to in that section, and executed it
(after making a few changes, as indicated in script,
and filling in user/pass as i had seen in man DBD::MySQL).
Result i got is :
------------------------------------------------------------------------
2 styles are supported:
Style 4: WHERE mycol = ? OR (mycol IS NULL AND ? IS NULL)
Style 6: WHERE mycol = ? OR (mycol IS NULL AND ? = 1)
------------------------------------------------------------------------
As to support for style 5, please note that i did not create a stored procedure,
since i do not yet know how to use these
(and also think that since query depends on a value in client,
procedure to execute would best be executed in client).
I expect that with current MySQL version stored procedure would work,
but older versions of MySQL do not support stored procedures.
Error messages of failures of other styles were :
style 0 : WHERE clause style 0 returned incorrect results.
style 1 : FUNCTION test.NVL does not exist
style 2 : syntax error near second argument of first ISNULL
style 3 : syntax error near third argument of DECODE
-------
I hope that this info is usefull to you, and that it be included in docs.
Thanks for providing perl, DBI, DBD, perldoc, etc...
Siward de Groot
(www.gransi.com/siward)
