Quoting Martijn van Oosterhout <[EMAIL PROTECTED]>:...
There already is an operator, and it is the ANSI SQL operator "IS". Just because "IS" does not use puctuation characters does not mean it is not an operator.You could create a new operator, but that means you'll have difficulty
moving it to any database that doesn't have that operator (which is most of
them).
Any commercial database vendor would be happy to make such a feature just for
that reason: to lock me in to their database :-). I do not try to stay database
neutral, and use lots of other features that will only work in postgresql.
An empty string is an empty string, and a NULL is the lack of there being a string, they are not the same. If you want to emulate what you have proposed then use the function "coalesce".If you want it to match perhaps you should forget NULL and use '' (zero
length string) instead.
Example:
select coalesce(string_column,'') from some_table ;
This will return an empty string for all records that have no data in string_column.
I have designed a number of realtime data collection programs, and when inserting only the available data into the proper columns of the table, I often end up will "NULL" columns because there was no data for that column. It is very usefull to know if you had data available or if the data was 0 or an empty string.
If you still don't understand, then use MySQL it is messed up and allows weird things like most of what you want to do.
Happy New Year
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