In search of rownum

Often people ask about various features supported by other RDBMS systems that Informix does not support.  I am rarely bothered by these issues, not because I don’t use Oracle, MySQL, PostgreSQL, or MS SQL Server – I don’t when I can help it – but rather because for the most part, the required functionality is either there in another form, is not really necessary, or can be emulated easily enough.

Examples are the INTERSECT and EXCEPT join operators.  Informix does not support either syntax. However, the results of an INTERSECT join are identical to the results of a normal INNER join with only columns from one of the tables included in the projection clause which is of course supported. The results of an EXCEPT are identical to those of a LEFT OUTER JOIN with only those values from the left table that do not match any rows in the right table r…

Auteur : noreply@blogger.com (Art Kagel)

No comments yet.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.