Column not found when performing SUM

Question

I’m developing the system for a school.

I need to create the vacation part.

For this I need to add the number of days already launched so that per year are not launched more than 30 days per employee.

For this I saw that there is the SUM function of SQL

However it keeps giving column error not found.

I checked and the name of the column is identical.

Can someone tell me what happened?

public void getSomaQuantidadeFerias(String rf, String exercicio) { ArrayList<Integer> total = new ArrayList<Integer>();
try {

        Connection con = new FabricaConexao("administracao").abrirConexao();
        PreparedStatement stmt = con.prepareStatement("select sum(quantidade_dias) from ferias_alunos WHERE rf =? AND exercicio ?");

        stmt.setString(1, rf);
        stmt.setString(2, exercicio);

        ResultSet rs = stmt.executeQuery();

        while(rs.next()){
        total.add(rs.getInt("quantidade_dias"));
        }


        for (int i = 0; i < total.size(); i++) {
            System.out.println(total.get(i));
        }
        System.out.println(total);

        rs.close();
        stmt.close();
        con.close();
    }

    catch (SQLException sql) {
        JOptionPane.showMessageDialog(null, "Deu ruim");
        sql.fillInStackTrace();
        System.out.println(sql.getLocalizedMessage());

        sql.printStackTrace();
    }

Error:

net.ucanaccess.jdbc.UcanaccessSQLException: UCAExc:::4.0.3 Column not found: quantidade_dias
at control.CrtTelaAdministracao.getSomaQuantidadeFerias(CrtTelaAdministracao.java:1008)
at view.TelaFeriasA$2.actionPerformed(TelaFeriasA.java:418)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)UCAExc:::4.0.3 Column not found: quantidade_dias

at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

Answer 1

Change your query to:

select sum(quantidade_dias) as quantidade_dias from ferias_alunos WHERE rf =? AND exercicio ?

The code rs.getInt("quantidade_dias") search for a result whose column name is quantidade_dias. The way your original query looks, it counts how many records there are, but it doesn’t name the result column name, which is why you get the missing column error message.