Tag Archives: sql macros

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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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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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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Dynamic Pivot with SQL Macros in Oracle 20c

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More than a year ago I blogged about my view on using Polymorphic Table Function (PTF) for dynamic pivot in Oracle 18c. Actually I was not as optimistic. The solution had at least two significant problems:

  • the function will not see any changes on the underlying data until new hard parse of the query
  • operating on bigger data sets returns multiple result rows: one per 1024 rows (the size of the row sets in PTF), thus requiring some post processing

With Oracle 20c we now have SQL macros and I was curious, whether they can help here.

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Temporal Joins with SQL Macros in Oracle 20c

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In a previous post on SQL macros in Oracle Database 20c we saw how SQL macros can be used to create a kind of “parameterized” views to establish a simplified access tier to temporal data. In this post I’d like to explore more possibilities to hide the complexity of SQL statements behind a functional syntax provided by using SQL macros. As an example we’ll stay with a temporal data introduced in the previous post and explore how we can do a temporal join of this versioned data.

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Parameterized Views in Oracle? No problem! With SQL macros!

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Views have always been an efficient tool for encapsulating complex logic, creating defined access structures and so on. But there is one thing views cannot do: accept parameters. And this is unfortunately a big disadvantage in terms of flexibility. As a result, there are a number of workarounds, none of them without their drawbacks.

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