The Wiert Corner – irregular stream of stuff

Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for the ‘PostgreSQL’ Category

PostgreSQL Exercises

Posted by jpluimers on 2023/01/11

[Wayback/Archive] PostgreSQL Exercises

This site was born when I noticed that there’s a load of material out there to help people learn about SQL, but not a great deal to make it easy to learn by doing. PGExercises provides a series of questions and explanations built on a single, simple dataset.

It was funny, as I bummped into right after writing the article Enabling GitHub pages to a HTML or markdown GitHub project is dead easy: Delphi deadlockempire is now hosted on (which reached the top of the blog queue yesterday).

After reading the [Wayback/Archive] PostgreSQL Exercises: Getting Started, start the exercises at [Wayback/Archive] PostgreSQL exercises: basic exercises.

There is no login needed, which I really like.

Note that some of the assignments are hard, and can have multiple results, see for instance [Archive] Fahru on Twitter: “this: … I FINALLY completed it, and any win is worth telling馃コ took me like one hour on and off. The “more than 30$” requirement is bizarre 馃槀 a bit different than the official answer so I’m digging up more about this learned a heck ton, worth the time! ” / Twitter

Via: [Archive] Steve Polito on Twitter: “If you’re like me and want to level up your SQL game, give PostgreSQL Exercises a try. …” / Twitter


Posted in Database Development, Development, PostgreSQL, Software Development, SQL | Leave a Comment »

Database fiddle sites

Posted by jpluimers on 2022/10/27

I knew there was JSFiddle for live playing around with JavaScript and more in your browser, so I wondered if there was a similar site for databases and SQL queries.

There are, so here are a few database fiddle sites: SQL playgrounds where you can live play with SQL queries (sometimes even without an underlying example database).

All via [Wayback/] database fiddle – Google Search:

Read the rest of this entry »

Posted in Conference Topics, Conferences, Database Development, DB2, Development, Event, Firebird, JavaScript/ECMAScript, JSFiddle, MariaDB, MySQL, OracleDB, PL/SQL, PostgreSQL, Scripting, Software Development, SQL, SQL Server, SQLite, T-SQL | Leave a Comment »

Case sensitivity for SQL identifiers 路 ontop/ontop Wiki 路 GitHub

Posted by jpluimers on 2021/07/08

For my link archive: [WayBack] Case sensitivity for SQL identifiers 路 ontop/ontop Wiki 路 GitHub:

  • Oracle and H2 changes unquoted identifiers to uppercase.
    Although technically possible, Oracle explicitly recommends to not use lowercase identifers. We do not support H2 with the setting DATABASE_TO_UPPER=FALSE, if this setting is enabled all queries with names and tables in lowercase must be quoted.
  • DB2 Names are not case sensitive.
    For example, the table names CUSTOMER and Customer are the same, but object names are converted to uppercase when they are entered. If a name is enclosed in quotation marks, the name becomes case sensitive. The schema name is case-sensitive, and must be specified in uppercase characters.
  • Postgres changes unquoted identifiers (both columns and alias names) to lowercase.
  • Mysql does not change the case of unquoted tables and schemas.
    It changes in lowercase the unquoted columns. Mysql tables are stored as files in the operating system the server runs on. This means that database and table names are not case sensitive in Windows, and case sensitive in most varieties of Unix or Linux. The backtick ` is used for enclosing identifiers such as table and column names.
  • Mssqlserver All connection string property names are case-insensitive.
    For example, Password is the same as password. Identifiers of objects in a database, such as tables, views, and column names, are assigned the default collation of the database. For example, two tables with names that differ only in case can be created in a database that has case-sensitive collation, but cannot be created in a database that has case-insensitive collation. Default SQL Server is not case sensitive. SELECT * FROM SomeTable is the same as SeLeCT * frOM soMetaBLe. Delimited identifiers are enclosed in double quotation marks (“) or brackets ([]). Identifiers that comply with the rules for the format of identifiers may or may not be delimited.


Posted in Database Development, DB2, Development, MySQL, OracleDB, PostgreSQL, SQL Server | Leave a Comment »

UUID/GUID as primary keys in databases; generating them from a .NET assembly

Posted by jpluimers on 2021/04/08

Some links for my archive:


Posted in .NET, Database Development, Development, PostgreSQL, Software Development, SQL Server | Leave a Comment »


Posted by jpluimers on 2021/02/18

[WayBack] showthedocs

is a documentation browser that finds the relevant docs for your code. It works by parsing the code and connecting parts of it to their explanation in the docs

, and supports these languages:

  • SQL
    • postgresql
    • mysql
  • Configuration
    • nginx
    • gitconfig

You can enter any language text, then click the language, followed by clicking the “SHOW ME THE DOCS!” button, for which an example is further below.

The site has an open architecture, allowing to plug in more languages and documentation:


gitconfig example

So for instance the below ./git/config file leads to this result [WayBack] where you can click on all the coloured areas for easy navigation through the documentation:

Read the rest of this entry »

Posted in *nix, *nix-tools, Database Development, Development, DVCS - Distributed Version Control, git, MySQL, nginx, PostgreSQL, Power User, Software Development | Leave a Comment »

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