Is it necessary to know many Programming languages or just 1-2 of them perfectly for a decent job?

Answer 1

In most cases one programming language isn't enough. Programming languages are mere tools that programmers use to go about solving a problem. An engineer just doesn't use one tool or two, he'll use whatever he can to get the job done. It's good to know many, knowing refers to how they work and being able to use/read them.

Answer 2

I've learned HTML, CSS, JavaScript & jQuery, PHP, MySQL, Visual Basic, FoxPro, C, C++, C#, XML, Java... and I suck in all of them