By chance when you set them as null did you use "null" or 'null' setting it as a string value? ______________________ Lucas Heuman
Phone 609.485.5401 "Martijn Tonies" <[EMAIL PROTECTED]> 05/01/2007 04:45 AM To "MySQL" <mysql@lists.mysql.com> cc Subject Re: IS NULL Question > I'm having problems understanding NULL. I grasp what a NULL value is, Actually, you don't :-) NULL is not a value, it's the lack of value and a state. A column can have 2 states: NULL or NOT NULL, which is part of the reason why SQL allows for the IS NULL and IS NOT NULL clause as opposed to checking for certain values with the equals operator ( MyColumn = 'My Value') > but I can't get NULL to perform correctly. For instance, if I do a > Select statement, I see that I have columns with a NULL value. > > select first, last, suffix from persons LIMIT 5; > +-----------+----------+--------+ > | first | last | suffix | > +-----------+----------+--------+ > | Benjamin | Page | NULL | > | Jonathan | Watson | NULL | > | Jose | Thorson | NULL | > | Alejandro | Nickels | NULL | > | Griselda | Richards | NULL | > +-----------+----------+--------+ > 5 rows in set (0.01 sec) > > Logically, it seems that a Select statement should find these five plus > any other NULL values in the suffix column. However, such a select > statment returns an empty set. > > mysql> select first, last, suffix from persons where suffix IS NULL; > Empty set (0.00 sec) > > Does anyone see what I'm doing wrong? (Thanks in advance for any help.) If the set is empty, the columns aren't NULL. Martijn Tonies Database Workbench - development tool for MySQL, and more! Upscene Productions http://www.upscene.com My thoughts: http://blog.upscene.com/martijn/ Database development questions? Check the forum! http://www.databasedevelopmentforum.com -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
