问题 (Update: As per Hans' suggestion, here's a suggestion to improve link.exe's behaviour, and you can vote for it if you have an account over there.) Okay, I'm a fool. In January I installed Oracle on my computer, Win7 Pro 64 Bit. I installed the 64 Bit version. Yesterday, using MSVC Express, I tried to compile and link a small test programm oci1.c against oci.h and oci.lib . cl /nologo /c /I%ORACLE_HOME%\oci\include oci1.c link /nologo oci1.obj /LIBPATH:%ORACLE_HOME%\oci\lib\msvc oci.lib My