i think you need more practice in sql server scenarios than knowledge, atleast try to learn sql server basic fundamentals,how sql server works, like architecture,how query work,what to do when database is in trouble, how to troubleshoot error,where to look for error, you can do all this things in your home laptop also by installing sql server and practice few scenario, you will know where you are weak and need improvement.

you can also practice according to the scenarios questions asked in interviews

you can check interview questions on forums of winmilestone.com / http://www.winmilestone.com/Topic?Interview