I had an email asking me how to get rid of the red lines after a schema change to the database in MS SQL Management Studio .
One of my new favorite shortcuts is to reload the intellisense with in the query window. If you make a change to the schema of a database your intellisense won't pick it up and you will have red lines under things you know exists. Hit the keys Ctrl + Shift + R to fix it.
If you have a bunch of Query windows open and you have been disconnected from the server you can reconnect those query windows just by going to the left pane top item right click and reconnect