嘗試從JTable中刪除的Java SQL語法錯誤

Question

我試圖一起從jtable和數據庫中刪除選定的行，但是我遇到語法錯誤。 可能是因為我使用的是varchar還是在這種情況下語法實際上是錯誤的？

    btnNewButton_2 = new JButton("Dzēst");
    btnNewButton_2.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            Statement statement = null;
            try {
                int tableRow = table_1.getSelectedRow();
                Object Kods = table_1.getValueAt(tableRow, 0);
                Object Nosaukums = table_1.getValueAt(tableRow, 1);
                Object Inventara = table_1.getValueAt(tableRow, 2);
                Object Uzskaites = table_1.getValueAt(tableRow, 3);
                Object Iegad = table_1.getValueAt(tableRow, 4);
                Statement stmt = null;
                Connection connection = ConnectDB();


                String sql = "DELETE FROM users " +
                       "WHERE Kods = " + Kods + " AND Nosaukums = '" + Nosaukums + "' AND Inventara Nr = " + 
                        Inventara  + " AND Uzskaites vertiba = '" + Uzskaites  + "' AND Iegades vertiba = " + Iegad;
                stmt = connection.createStatement();
               stmt.executeUpdate(sql);

            } catch (SQLException ex) {
                Logger.getLogger(dddddddd.class.getName()).log(Level.SEVERE, null, ex);
                  JOptionPane.showMessageDialog(null, "Nav ievadita visa informacija");
            }

錯誤：

You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'Nr = ttttt AND Uzskaites vertiba = '3.0' AND Iegades vertiba = 3.0' at line 1

數據庫變量：

Kods -Index -int(255)       
Nosaukums - varchar(255)         
Inventara Nr - varchar(255)  
Uzskaites vertiba - float                
Iegades vertiba - float

Answer 1

請注意，您的列具有以空格分隔的名稱。 通常，使用這種命名約定不是最佳實踐，但是使用snake_case或CamelCase。

對於您的情況，您需要正確引用您的列名，例如

WHERE `Inventara Nr` = '33'

請注意，盡管您的代碼容易受到SQL注入的攻擊。 我建議閱讀有關它們的文章。 您應該始終使用PreparedStatements 。