通過java搜索整數類型數據庫字段

Question

我想通過提供一個憑證號碼作為搜索條件來搜索數據庫，但保證號碼是整數，所以我不能用以下代碼執行此操作，請為此建議一些其他代碼。

  try{
            String sql = "select item_type as 'Item Type', md_by as 'Made By', model as       'Model', selling_price as 'Selling Price', purchase_price as 'Purchase Price', purchase_date as 'Purchase Date', vouch_no as 'Voucher No.', vouch_date as 'Voucher Date', record_no as 'Record No.' from purchase" where vouch_no = ?;
            ps = con.prepareStatement(sql);
            ps.setString(1 , txt_vouchno_p.getText());
            rs = ps.executeQuery();
            Table_p.setModel(DbUtils.resultSetToTableModel(rs));


        }   
        catch(SQLException ex){

                JOptionPane.showMessageDialog(null, "Error: " + ex);

        }
        catch(Exception ex){
            JOptionPane.showMessageDialog(null, "Error: " + ex);
        }

Answer 1

使用Integer#parseInt將txt_vouchno_p.getText()的值轉換為int並相應地將其傳遞給PreparedStatement ：

ps.setInt(1, Integer.parseInt(txt_vouchno_p.getText()));

---

看起來像是當前代碼中的拼寫錯誤，但對於大型文字String ，不要害怕將它分成幾行，編譯器足夠聰明，可以將它轉換為單個大String 。 所以，這一行：

String sql = "select item_type as 'Item Type', md_by as 'Made By', model as       'Model', selling_price as 'Selling Price', purchase_price as 'Purchase Price', purchase_date as 'Purchase Date', vouch_no as 'Voucher No.', vouch_date as 'Voucher Date', record_no as 'Record No.' from purchase" where vouch_no = ?;

應改寫為：

String sql = "select item_type as 'Item Type'"
    + ", md_by as 'Made By'"
    + ", model as 'Model'"
    + ", selling_price as 'Selling Price'"
    + ", purchase_price as 'Purchase Price'"
    + ", purchase_date as 'Purchase Date'"
    + ", vouch_no as 'Voucher No.'"
    + ", vouch_date as 'Voucher Date'"
    + ", record_no as 'Record No.'"
    + " from purchase"
    + " where vouch_no = ?";

Answer 2

您的代碼中有一個簡單的錯誤（“其中vouch_no ...”不在字符串sql中），它應該是：

 String sql = "select item_type as 'Item Type', md_by as 'Made By', model as       'Model', selling_price as 'Selling Price', purchase_price as 'Purchase Price', purchase_date as 'Purchase Date', vouch_no as 'Voucher No.', vouch_date as 'Voucher Date', record_no as 'Record No.' from purchase where vouch_no = ?";

您可以像這樣設置參數：

ps = con.prepareStatement(sql);
ps.setString(1 , Integer.parseInt(txt_vouchno_p.getText()));