Going through Oracle documentation (yes, I do that sometimes), I found the CREATE OPERATOR command. This command allows you to create user-defined operators. To quote psoug reference:

Oracle allows developers of object-oriented applications to extend the list of built-in relational operators (for example, +, -, /, *, LIKE, AND, OR) with domain specific operators (for example, […]

I had a requirement to write a query that should return a concatenation of column values from different rows and grouped by another column. Well, that would be easy if Oracle provided an aggregate function similar to SUM or COUNT for example, but instead of summing or counting, it would concatenate. Alas! There is no […]