SQL Tabs

SQL Tabs is a no-nonsense and fairly capable SQL client that offers you a simple environment to execute queries, run scripts and explore database objects.
Straightaway, you should know that this simplistic utility is capable of working with PostgreSQL, MySQL, MS SQL, MariaDB, and Amazon Redshift databases. It's also worth pointing out that it can be run just as easily on all major OSes out there, namely Windows, macOS, and Linux.

Can be launched with the minimum of effort on your part

Getting started with SQL Tabs is hardly challenging since the utility can be launched without the need of installation. Please take into account that this is not the most user-friendly SQL client out there, as it is mainly intended for users that already know a thing or two about databases.
The app sports a tabbed user interface with a strong focus on simplicity. Connecting to a database requires you to enter the username, host, port number, database name, and password, if necessary, in the following format: "protocol://user@host:port/dbname".

Packs all the basic features you would expect from an SQL client

That said, you can access the app's main features from the Database menu, located up top. You can explore the object within your database, run scripts, execute blocks, break executions, and even get a complete history of all the executed queries.
It's also worth mentioning that SQL Tabs makes it possible for you to create comprehensive charts based on your query results. Markdown rendering support, rich scripts output, two editing modes (Classic and Vim), two UI themes, as well as the possibility to export your work to JSON and CSV are some extra features that might arouse your interest in this app.

Pragmatic and simplistic, cross-platform SQL client

All in all, if you're not learning the ropes of database languages and you're looking for a minimalist yet capable SQL client, the SQL Tabs should be definitely on your list of possible options.