I'd like to know if there is some open source web front-end for databases. I'd like something where queries can be executed from a web browser, only read-only queries are fine. If possible it would be great to be able to select with a gui the columns that are displayed as the result of the query.
As several people asked me, I use Oracle. I'd prefer open source to be able to customize if needed.
For MySQL, phpMyAdmin is the only open source tool I'm aware of. I'm not sure about other types of databases.
I've used one called myLittleAdmin for SQL Server, but it's a closed-source paid product. Probably not going to be much help there.
MySQL has phpMyAdmin, which is quite good.
For Oracle and SQL Server there's Maestro.
It depends on wich database you are going to use, i have used phpMyAdmin before and it is really nice.
phpMyAdmin is a free software tool written in PHP intended to handle the administration of MySQL over the World Wide Web. phpMyAdmin supports a wide range of operations with MySQL. The most frequently used operations are supported by the user interface (managing databases, tables, fields, relations, indexes, users, permissions, etc), while you still have the ability to directly execute any SQL statement.
For a PHP/MySQL standard setup, I've found SQLBuddy to be a great (and free) little utility. It's really simple, has almost no install, and it is friendly to use. phpMyAdmin can be a bit overkill for some people especially if you're just messing around with the database and wanna check if your entries were inserted. Check it out.
Not good for you if you're using Oracle but as well as phpMyAdmin, there is also phpPgAdmin for us folks who use Postgres.