Java Swing-條件SQL查詢

Question

我有一條sql select語句，通過從jComboBox＆jDateChooser獲取用戶輸入信息，可以通過jButton在jtable上顯示查詢。

是否可以為按鈕設置條件，例如

下面的代碼為jButton動作lisener

    java.util.Date dateFromDateChooser = jDateChooser.getDate();
    String dateString = String.format("%1$tY-%1$tm-%1$td", dateFromDateChooser);  

    String attendant = (String) cbName.getSelectedItem();
    String fill = "SELECT id as 'No', recDate as 'Date', super as 'Supervisor', attendant as 'Attendant' from log"
            + "WHERE recDate = '"+dateString+"'"
            + "and attendant = '" + attendant + "'";

    try{

        ps = conn.prepareStatement(fill);
        rs = ps.executeQuery();    
        jTable1.setModel(DbUtils.resultSetToTableModel(rs));

    }
    catch(Exception e){
        JOptionPane.showMessageDialog(null, e);
    }

上面的代碼工作正常，但是我希望允許用戶使用兩種類型的條件。 例如通過選擇“日期和jComboBox”或僅選擇“日期”來顯示搜索結果

我可以使用if else else語句嗎？

請指教...

Answer 1

將檢查添加到您的SQL建築物

String fill = "SELECT id as 'No', recDate as 'Date', super as 'Supervisor', attendant as 'Attendant' from log"
        + "WHERE recDate = '"+dateString+"'";

if(comboboxShouldBeIncluded) {
        fill+= " and attendant = '" + attendant + "'";
}

Answer 2

如果未選擇姓名，則無需服務員查詢

String attendant = (String) cbName.getSelectedItem();
    String qry;
    if( attendant != null && !attendant.isEmpty() ) {
     qry = "SELECT id as 'No', recDate as 'Date', super as 'Supervisor', attendant as 'Attendant' from log"
            + "WHERE recDate = '"+dateString+"'"
            + "and attendant = '" + attendant + "'";
    } else {
        qry = "SELECT id as 'No', recDate as 'Date', super as 'Supervisor', attendant as 'Attendant' from log"
            + "WHERE recDate = '"+dateString+"'";
    }