Question

我无法通过编辑/更改单元格值并单击更新按钮来更新数据库中的数据，但他无法更改我更改为单元格的数据库。它与最后一个值仍然相同。

这是我的代码：

    public void directlyup() {
       int col=tablesample.getSelectedColumn();
       int row=tablesample.getSelectedRow();  
       int index;
       index = Integer.parseInt(tablesample.getModel().getValueAt(row, 0).toString());
        try { 
            String sql ="UPDATE invoice SET description = ?,qty = ?,unitprice = ?" 
                    + ",total = ? WHERE id ="+row;
            pst = conn.prepareStatement(sql);
            pst.setString(1, (String) tablesample.getValueAt(row, 1));
            pst.setString(2, (String) tablesample.getValueAt(row, 2));
            pst.setString(3, (String) tablesample.getValueAt(row, 3));
            pst.setString(4, (String) tablesample.getValueAt(row, 4)); 
            pst.execute(); 
            JOptionPane.showMessageDialog(null, "Successfully Updated"); 
        } catch (Exception e) {
         JOptionPane.showMessageDialog(null, e);
        }
    }

Answer 1

String sql ="UPDATE invoice SET description = ?,qty = ?,unitprice = ?" 
                + ",total = ? WHERE id ="+row;

为什么要尝试在where子句的SQL中嵌入变量？

只需使用与其他值相同的参数即可。它将使SQL更简单：

String sql =
    "UPDATE invoice SET description = ?, qty = ?, unitprice = ?, total = ? WHERE id = ?";
...
pst.set???(5, row);

Answer 2

对于数据集上的CRUD操作，最好使用中间表。这避免了大量数据集上的大量查询。

在提出解决问题的建议之前，我想指出一些关于数据库结构的评论：

total字段显然是计算字段。这样的信息不适合放入数据库。它是根据要求计算的。
整套数据显然是文件（发票）的一部分。因此，数据库中必须有一个字段，用于唯一标识数据所涉及的文档。

另外，我想说这样的决定是针对特定的数据库做出的。在这种情况下，我的解决方案涉及mysql 。

这是底部代码段运行的表格的DDL

CREATE TABLE `invoice` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `invoice_id` int(10) unsigned NOT NULL,
  `description` varchar(255) DEFAULT NULL,
  `qty` double DEFAULT NULL,
  `unitprice` double DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB

这是使用文档ID密钥（invoce_id）对数据集进行CRUD操作的代码。

public boolean save(long invoice_id, List<Invoice> list) throws SQLException {
    try(Connection connection = getConnection()) {
        try {
            connection.setAutoCommit(false);

            String query =
                    "create temporary table if not exists `invoice_tmp` (" +
                            "`id` int(10) unsigned NOT NULL," +
                            "`description` varchar(255) DEFAULT NULL," +
                            "`qty` double DEFAULT NULL," +
                            "`unitprice` double DEFAULT NULL)";

            connection.createStatement().executeUpdate(query);

            query = "insert into `invoice_tmp` values (?, ?, ?, ?)";
            PreparedStatement statement = connection.prepareStatement(query);
            for(Invoice invoice: list) {
                statement.setLong(1, invoice.getId());
                statement.setString(2, invoice.getDescription());
                statement.setDouble(3, invoice.getQty());
                statement.setDouble(4, invoice.getUnitPrice());

                statement.addBatch();
            }

            statement.executeBatch();
            statement.close();

            query =
                    "delete invoice from invoice " +
                    "left join invoice_tmp on (invoice.id = invoice_tmp.id) " +
                    "where invoice_id = ? and invoice_tmp.id is null";

            statement = connection.prepareStatement(query);
            statement.setLong(1, invoice_id);
            statement.executeUpdate();
            statement.close();

            query =
                    "update `invoice` " +
                    "join `invoice_tmp` using (`id`) " +
                    "set " +
                            "`invoice`.description = `invoice_tmp`.description, " +
                            "`invoice`.qty = `invoice_tmp`.qty, " +
                            "`invoice`.unitprice = `invoice_tmp`.unitprice";

            connection.createStatement().executeUpdate(query);

            query =
                    "insert into `invoice` (`invoice_id`, `description`, `qty`, `unitprice`) " +
                    "select ? as `invoice_id`, `description`, `qty`, `unitprice` from `invoice_tmp` where `id` = 0";

            statement = connection.prepareStatement(query);
            statement.setLong(1, invoice_id);
            statement.executeUpdate();
            statement.close();

            connection.createStatement().executeUpdate("drop table if exists `invoice_tmp`");

            connection.commit();
            return true;
        }
        catch (Exception e) {
            connection.rollback();
            throw e;
        }
    }
}

this是一个测试项目，用于演示上述代码的工作原理。

Answer 3

您可能打算在WHERE子句中使用索引而不是行？

String sql ="UPDATE invoice SET description = ?,qty = ?,unitprice = ?" 
                + ",total = ? WHERE id ="+index;

Answer 4

假设您选择了多行，如果您的id为int：

    int[]rows=tablesample.getSelectedRows();


String sql="UPDATE invoice SET description = ?,qty = ?,unitprice = ?" 
        + ",total = ? WHERE id =?";

try{
    PreparedStatement pst = conn.prepareStatement(sql);
    for(int currentRow:rows){


                 pst.setString(1, (String) tablesample.getValueAt(currentRow, 1));
                 pst.setString(2, (String) tablesample.getValueAt(currentRow, 2));
                 pst.setString(3, (String) tablesample.getValueAt(currentRow, 3));
                 pst.setString(4, (String) tablesample.getValueAt(currentRow, 4));
                 pst.setInt(5,  currentRow);
                 pst.executeUpdate(); 



       }
    JOptionPane.showMessageDialog(null, "Successfully Updated");
   } catch (Exception e) {
      JOptionPane.showMessageDialog(null, e);
     }  finally{
         try {
            conn.close();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
     }

为了获得最佳性能，您可以像example

一样使用executeBatch

java -update数据库通过编辑单元格不起作用？

4 个答案: