如果id已经存在，Java更新mysql行

Question

我有一个包含 5 个字段的简单表单。 (txtID、txtFirstName、txtLastName、txtCheque、txtSavings)。我想要做的就是将这些字段插入到我的数据库表“帐户”中。在那一步之前，我想检查我的 txtID 字段中的 ID 是否已经存在于我的数据库中。如果是，那么我想用字段中的内容更新数据库行。如果不是，我想用内容创建一个新行。到目前为止，检查 ID 是否存在于我的数据库中有效，但如果单击我的 btn，我会收到以下错误消息:我不知道我做错了什么。

com.mysql.jdbc.exceptions.MySQLSyntaxErrorException: 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 '(LastName, FirstName,Cheque,Savings) VALUES('Tester','Markus','450.00','50.00" at line 1

private void btnUpdateActionPerformed(java.awt.event.ActionEvent evt) {                                          
        // TODO add your handling code here:
        try{
            String id = txtID.getText();
            String checkid ="SELECT * FROM accounts where ID=?";
            pst=conn.prepareStatement(checkid);
            pst.setString(1, id);
            rs = pst.executeQuery();

            boolean recordAdded = false;
            while(!rs.next()){            
                 recordAdded = true;
            }
            if(recordAdded){
              // the statement for inserting goes here.
            }else{
                String sql ="UPDATE accounts SET " + "(LastName,FirstName,Cheque,Savings) VALUES" + "(?,?,?,?)";
                pst=conn.prepareStatement(sql);
                pst.setString(1,txtLastName.getText());
                pst.setString(2,txtFirstName.getText());                
                pst.setString(3,txtCheque.getText());
                pst.setString(4,txtSavings.getText());
                pst.executeUpdate();
                getAllAccounts();
                JOptionPane.showMessageDialog(null, "Customer Updated");
            }

        }
        catch(Exception e){
            JOptionPane.showMessageDialog(null, e);
        }
        finally {
            try{
                rs.close();
                pst.close();
                getAllAccounts();
            }
            catch(Exception e) {
            }
        }
    }

Answer 1

你让我对你的代码做一些修改吗？

private void btnUpdateActionPerformed(java.awt.event.ActionEvent evt) {                                          

    try {

        String sql = "UPDATE accounts SET LastName = ?, FirstName = ?, Cheque = ?, Savings = ? where id = ?";
        pst=conn.prepareStatement(sql);
        pst.setString(1,txtLastName.getText());
        pst.setString(2,txtFirstName.getText());                
        pst.setString(3,txtCheque.getText());
        pst.setString(4,txtSavings.getText());
        pst.setString(5,txtID.getText());
        int updatedRowCount = pst.executeUpdate();
        // no record with id = txtID
        if(updatedRowCount == 0) {

            pst.close();                

            sql = "insert into accounts (ID,LastName,FirstName,Cheque,Savings) values (?,?,?,?,?,?) ";
            pst = conn.prepareStatement(sql);
            pst.setString(1,txtID.getText());
            pst.setString(2,txtLastName.getText());
            pst.setString(3,txtFirstName.getText());
            pst.setString(4,txtCheque.getText());
            pst.setString(5,txtSavings.getText());
            pst.executeUpdate();

        }

        getAllAccounts();
        JOptionPane.showMessageDialog(null, updatedRowCount > 0 ? "Customer Updated" : "Customer Inserted");

    }
    catch(Exception e){
        getAllAccounts();
        JOptionPane.showMessageDialog(null, e);
    }
    finally {
        try{
            pst.close();
        }
        catch(Exception e) {
        }
    }
}