Fix two warnings

See issue #1828.

src/sql/Query.cpp

@@ -81,7 +81,7 @@ std::string Query::buildQuery(bool withRowid) const
     std::string order_by;
     for(const auto& sorted_column : m_sort)
     {
-        if(sorted_column.column < m_column_names.size())
+        if(sorted_column.column < static_cast<int>(m_column_names.size()))
             order_by += sqlb::escapeIdentifier(m_column_names.at(sorted_column.column)) + " "
                     + (sorted_column.direction == sqlb::Ascending ? "ASC" : "DESC") + ",";
     }

src/sqlitetablemodel.cpp

@@ -221,7 +221,8 @@ int SqliteTableModel::filterCount() const
 }
 
 // Convert a number to string using the Unicode superscript characters
-static QString toSuperScript(int number)
+template<class T>
+static QString toSuperScript(T number)
 {
     QString superScript = QString::number(number);
     superScript.replace("0", "⁰");
@@ -247,7 +248,7 @@ QVariant SqliteTableModel::headerData(int section, Qt::Orientation orientation,
         // if we have a VIRTUAL table the model will not be valid, with no header data
         if(section < m_headers.size()) {
             QString sortIndicator;
-            for(int i = 0; i < m_query.orderBy().size(); i++) {
+            for(size_t i = 0; i < m_query.orderBy().size(); i++) {
                 const sqlb::SortedColumn sortedColumn = m_query.orderBy()[i];
                 // Append sort indicator with direction and ordinal number in superscript style
                 if (sortedColumn.column == section) {