public static ExprNodeDesc toExprNode(ColumnInfo columnInfo, RowResolver rowResolver)
      throws SemanticException {
    ExprNodeDescExprFactory factory = new ExprNodeDescExprFactory();
    return factory.toExpr(columnInfo, rowResolver, 0);
  }
Transforms column information into the corresponding Hive ExprNode.
ql/src/java/org/apache/hadoop/hive/ql/parse/type/ExprNodeTypeCheck.java