Enumerate columns in result_set

spec/result_set_spec.cr

@@ -41,5 +41,19 @@ describe DB::ResultSet do
       end
       the_rs.closed?.should be_true
     end
+
+  it "should enumerate columns" do
+    cols = [] of String
+
+    with_dummy do |db|
+      db.query "3,4 1,2" do |rs|
+        rs.each_column do |col, col_type|
+          cols << col
+          col_type.should eq(Slice(UInt8))
+        end
+      end
+    end
+
+    cols.should eq(["c0", "c1"])
   end
 end

src/db/result_set.cr

@@ -41,6 +41,13 @@ module DB
       end
     end
 
+    # Iterates over all the columns
+    def each_column
+      column_count.times do |x|
+        yield column_name(x), column_type(x)
+      end
+    end
+
     # Move the next row in the result.
     # Return `false` if no more rows are available.
     # See `#each`