Multi-step exec support (#27)

spec/db_spec.cr

@@ -119,4 +119,12 @@ DB::DriverSpecs(DB::Any).run do
       end
     end
   end
+
+  it "handles single-step pragma statements" do |db|
+    db.exec %(PRAGMA synchronous = OFF)
+  end
+
+  it "handles multi-step pragma statements" do |db|
+    db.exec %(PRAGMA journal_mode = memory)
+  end
 end

src/sqlite3/statement.cr

@@ -19,7 +19,11 @@ class SQLite3::Statement < DB::Statement
     end
 
     # exec
-    step = LibSQLite3::Code.new LibSQLite3.step(self)
+    step = uninitialized LibSQLite3::Code
+    loop do
+      step = LibSQLite3::Code.new LibSQLite3.step(self)
+      break unless step == LibSQLite3::Code::ROW
+    end
     raise Exception.new(sqlite3_connection) unless step == LibSQLite3::Code::DONE
 
     rows_affected = LibSQLite3.changes(sqlite3_connection).to_i64