Author Archives: Erik van Roon

It’s so easy to pick the wrong one                                         #JoelKallmanDay

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I started this blog enthusiastically. And then life happened. Today is Joel Kallman Day, so it seems a good day to pick this up again. Some time ago I ran into a problem with my code, where the cache for a result cache function wasn’t invalidated if DML was performed on the table the function selected from.This led to the function returning old values because it was under the impression the cache was still valid.I’ve checked and seen this behavior in all versions between 12.1.0.2 and the currently highest available version 23c FREE. In the end it turned out to be caused by a “for update” clause that I unintentionally copied when I put the query into the function from someplace else.So, it wouldn’t have happened if paid more attention to what I was copying.Nevertheless, the combination of a result cache and a “for update” is as far as I … Continue reading →

Your library is your paradise

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Update 14-07-2021 I just tried SQLcl latest version 21.2. First results: The registering of my custom commands with below library doesn’t work anymore. Could be my bad, in which I’ll try to fix it, could be something in SQLcl. I don’t know yet, have to investigate as soon as I have the time. For now: Either don’t use this library, or stick to 21.1.1 until the root cause is fixed. Update 08-10-2021The above mentioned problem was not due to my code, so the library can be safely used. It’s caused by new stuff inside SQLcl.So, if you run javascript code and only receive one of these messages:“!ScriptCommand.1!”“JS Language engine not found”The quickest way to solve it is to install JDK. (Or better yet: GraalVM. See next update.) Update 14-04-2022On 07-04-2022 version 22.1 of SQLcl was released which ends support for Java 8.So, as of that version Java 11 is the … Continue reading →

Hit the road Jack, and don’t you come back no more….

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In my blogpost “Being in command“, about custom commands I said that I couldn’t find a way to unregister  a registered custom command, other than restarting SQLcl.That is still true. I couldn’t.But Philipp Salvisberg could. He was able to find a way to do just that. That means that with his hard work as input, we are now able to Unregister a previously registered custom command.That makes it possible to register the command in an edited new version without the need to restart SQLcl. So, like Jack in the famous song, let’s try to kick a registered custom command out of our SQLcl house. Go straight to Introduction First of all: this post will deal with the code needed to unregister a custom command.In my humble opinion just, like registering a command, it takes too much code and effort to be considered user friendly.In my next blog post I will … Continue reading →

Being in command

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This post is the third one of three that together are an introduction to scripting in SQLcl.Also read part 1 and part 2. In the previous post I’ve created functionality for SQLcl that it doesn’t have “out of the box”.In this post I’ll continue to build on that script, but the information here is valid for any JavaScript script you develop for SQLcl. In short: I built some functionality in JavaScript that can read a client file and place the contents in a bindvariable.This script resides in a file called “file2bind.js” so we can use it by telling SQLcl we want to run a script with this name and certain parameter values.Executing that script is done using the built in command “script” As I’ve said a couple of times in that post: I’m lazy.So typing “script ” every time I want to execute this script will get on my nerves … Continue reading →

A Person who won’t read has no advantage over one who can’t read

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This post is the second one of three that together are an introduction to scripting in SQLcl.Also read part 1 and part 3. The title of this blogpost is (supposedly) a quote from Mark Twain, and I completely agree with it.I was reminded of this quote when I was working on the subject of this blogpost. In SQL*Plus you can’t read the contents of a client file.Well, to be honest, you can do “get scriptname.sql” to place the contents of a SQL script in the execution buffer.Or you could copy the file you want to read to the server and use utl_file or an external table definition.But other than that, nothing.No way to just read the contents of any client file. Ok, SQL*Plus is limited, no news there.Let’s turn to the favorite command line tool of the 21st century, SQLcl. SQLcl is capable of reading client files and processing them. … Continue reading →

When great just isn’t good enough

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This post is the first one of three that together are an introduction to scripting in SQLcl.Also read part 2 and part 3. For many years now SQLcl is my favorite command line tool to connect to Oracle databases. (available at the bottom of the SQL Developer download page)It does (practically) everything SQL*Plus does and a whole lot more. It has many capabilities that SQL*Plus just doesn’t have.But this post is not about those goodies SQLcl delivers, it’s more or less about what is doesn’t…. No matter how good we think a tool is, and I think SQLcl is great, there will always be things missing, or not quite the way we would want them to be.SQLcl is no exception to this rule.Inevitably we run into something that makes us think “I wish it could do ….”.The team that brings us SQLcl (and SQL Developer and Datamodeler and ORDS) is … Continue reading →