My recommendation is that you become familiar with both databases, because they each have different strengths. MySQL is definitely easier for smaller jobs, general dynamic websites, etc...
However for serious web-based applications, PostgreSQL has more features in common with the "serious" DB platforms, such as Oracle, DB2, etc... You might find that MySQL seems easy at first, but you can end up painting yourself into a corner. I am just going through this with one web-based application I am developing:
The client ended up greatly increasing the scope of the application, while I was still developing it. I had originally decided on PHP/MySQL, because it was to be hosted by their ISP. By the time the scope began to increase, it became obvious that we would need a specialized server. With the complicated relationships I had to build between tables, it would have been muich easier to start with PostgreSQL, having full foreign key constraints, with cascading deletes, etc... Now, in order to keep the application running in MySQL, I have had to write several ugly hacks, and am soon planning to switch the whole thing to PostgreSQL. -------------------
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