Category Archives: Oracle

How to get the final SQL after macro expansion

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In my very first post about SQL macros, I mentioned that for table macros, there is a simple way to see the SQL statement after macro expansion using dbms_utility.expand_sql_text. However, for scalar SQL macros, there is no such straightforward method. We can activate a CBO trace (also known as event 10053) and find the final statement in the trace file. This approach works for both scalar and table SQL macros. In this post, we will explore how to do this, and we will use… a SQL macro for that! Well, at least we will give it a try…

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Null Values? NOT IN my Subquery! #JoelKallmanDay

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I had to learn from this mistake more than once in my SQL career, until it became a kind of reflex: always think about the NULL values when you are writing a NOT IN subquery. Well, you should ALWAYS keep the NULL values in mind as a SQL developer, but in this case the consequences can be really nasty! And it drives me crazy how many times I’ve seen this error in my consulting life, even in production code. So, what is the point here?

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What does ChatGPT “think” about SQL Macros?

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After some weeks of reading and hearing in almost every news report about generative AI and ChatGPT in particular, and how it will change a developer’s life or even make developers obsolete, I was really curious to check it out myself and ask some developer questions. Since I’ve posted quite lot about SQL macros in the past few years, I thought aksing about them could be a good start point. One more argument to start with the topic I’m pretending to know lot about, is to be able to easily distinguish the truth from AI hallucination.

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Comparing Rows using a SQL Macro

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After the previous post about building an UNPIVOT query via SQL macro to output table rows like key-value pairs, I thought of another use case for the UNPIVOT operator, where developing a reusable SQL macro will make sense. From time to time you need to spot the difference between almost identical rows. You know they are different and you can easily check this using MINUS or GROUP BY, but if you want to know in what column(s) exactly the difference is, you need another approach.

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Yet another PRINT_TABLE – as a SQL Macro!

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A few weeks ago Jonathan Lewis has published a note about Tom Kyte’s print_table – a small PL/SQL procedure to output each row in a table as a list of (column_name , value). And since this note has gained some comments with other implementations, here is my contribution. Guess how? Of course with a SQL macro.

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Not Every “Not Equals” is Equal

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Yesterday I voted on the poll by @SQL Daily about using different forms for “not equals” conditions and that brought back bad (and funny) memories. Over 25 years I have always used “!=”. “Does it matter”, you might ask? Actually, it shouldn’t. But here is my story and the reason, why I was considering to change my habits and use “<>”.

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Using Subqueries and Views with PTF or SQL macros

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In the last post about SQL macros in 19c I tried to use a subquery as an input for the function. And when I had some DATE calculations in a query, I got ORA-62558: Unsupported data types (DATE) The result looked somewhat confusing at first, but if you think about it, it is logical and maybe not a bug at all. You should just be very explicit while using subqueries and views(!) in this scenario. And because this behavior is not documented, it is worth sharing, I think.

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SQL macros in Oracle 19c

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Now that I have created a patched Oracle database docker image with Release Update 19.8 (19.8.0.0.DBRU:200714) to play with, I can finally start testing the backport of SQL macros! (UPDATE: As of now you can play with SQL macros on Autonomous Databases in Oracle Cloud (also free tier!) and on livesql.oracle.com)

SQL Macros have been introduced in Oracle 20c. As of now, Oracle 20c is only available as preview version in Oracle Cloud. That’s why I was quite excited when Connor McDonald pointed out on Twitter that they were backported to 19c. Let’s see if it works, and how.

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Upgrading a 19c database on docker

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I’m neither an Oracle DBA, nor am I a Docker expert. How on earth did I get here to write this post? Well, I’m still an Oracle Developer and as you may have noticed, I was recently focused on SQL macros. It is a new feature of Oracle Database 20c, but obviously so awesome that it was backported to 19.6.0. Of course I asked myself, how can I start testing SQL macros in 19c?

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