Why is the DLL file of the copied project missing?

The first time I got in touch with QT today, I just installed version 4.7 and ran it on vs2008. I was prompted that a DLL file was missing and I was prompted to reinstall it. I have re-installed it once (no experience). The result is still like this. I thought about how to put the DLL into Debug. Is that good? So I went down and put it into debug, however, I think this should not be the case. The missing DiI should be installed in the SDK. Why didn't I find it? I suddenly thought that when I installed the Java SDK before, you also need to configure the PATH variable of the system. It seems that when the program is running, you can find the DLL file in the SDK. So I added the installation bin directory of QT to the path, the result is really good. For the first time, I connected the previous things with the new things I learned. this problem will not waste so much time in the future. the following section describes the QT environment. first install
Vs2008, then install the corresponding assist. then download the compiled qt4.7 version of vs2008: Release