I am using cross sectional survey data for 3-4 different years. I think I need to rename most variables (with similar descriptions but different names in each dataset) to match each other, and also create a year variable in each dataset since year will be my key explanatory variable (I want to estimate the causal effect of an event in 2012-so I will compare 2012 and the years after 2012 to 2011). Is this correct? I am finding it really hard to compare across over 5000 variables per dataset, is there a way to open multiple datasets simultaneously, or any other shorter way to do this?

Many thanks for your help!