INFOs needed: Tools behind relational DBMS

Hello world, I want to find out, which tools exists around some database systems. This may a interesting thing before making a decision to buy one or get a generally overview about these existing applications. Especially I need some advices from people who made experiences with: * design (E-R-modelling, ...), * development (database schemas, (4GL?) forms), * and application tools ( may be called 'front ends', support for writing my own dbms applications) for the DBMS Oracle, Sybase, Ingres and Informix. How powerfull are they, how friendly to new user (yes, I'm also one :-), how long does it takes me to work with it, what was the difficultest point you had to master (common, say, what was enough to make you weep...).. I know, that's a globally question, but I mean there's a globally interest. If so, I would post a summary. Hope of experts and interests! Ingo