title: SparkSQL parsing - SqlBase.g4 doesn't recognize lowercase keyword and identifiers
body: <p>I downloaded SqlBase.g4 and use the antlr v4 tool to build the lexer and parser. However, when I run the parser against a very simple query: <code>select * from table1</code> , it can't recognize the lowercase <code>select</code> and lowercase table identifier <code>table1</code>, when I change the query to <code>SELECT * FROM TABLE1</code> it works.</p>
  
  <p>Is there a way to let the parser work for the lowercase scenario?</p>