Question

我正在尝试创建一个sql查询构建器类型程序，该程序使用用户输入数据为表构建自定义查询

到目前为止我已经

了

public int checkBetweenDates() throws SQLException{
        String t1 = "2015-07-08"; //or later some user input variable
        String t2 = "2015-07-09";//or later some user input variable
        String id = "22 03 E7 99";//or later some user input variable
        int rowCount = -1;
        //Statement stmt = null;        

        String dateChoice = "select count(*) " 
                + "from dancers " 
                + "where ts between (t1) and (t2)"
                + "and id = (id)"
                + "values (?)";

        Connection conn = DriverManager.getConnection(host, username, password);
        System.out.println("Connected:");
         PreparedStatement preparedStmt = (PreparedStatement) conn.prepareStatement(dateChoice);
         preparedStmt.setString    (1, t1);
//       preparedStmt.setString    (2, t2);
//       preparedStmt.setString    (3, id);
        // stmt = conn.createStatement();
        ResultSet rs = preparedStmt.executeQuery(dateChoice); 
        try {
                rs = preparedStmt.executeQuery(dateChoice);
                rs.next();
                rowCount = rs.getInt(1);
                System.out.println(rowCount);
            }
         catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        finally {
            rs.close();
            preparedStmt.close();
        }
        return rowCount; 

    }

所以它连接并且一切正常，但是它没有执行查询说sql语法错误的值（？，？，？）

任何帮助都会很棒，谢谢你们！

卡尔

Answer 1

尝试此操作，查询中的更改以及设置预准备语句参数

public int checkBetweenDates() throws SQLException{
        String t1 = "2015-07-08"; //or later some user input variable
        String t2 = "2015-07-09";//or later some user input variable
        String id = "22 03 E7 99";//or later some user input variable
        int rowCount = -1;
        //Statement stmt = null;        

        String dateChoice = "select count(*) " 
                + "from dancers " 
                + "where ts between ? and ?"
                + "AND id = ?";

        Connection conn = DriverManager.getConnection(host, username, password);
        System.out.println("Connected:");
         PreparedStatement preparedStmt = (PreparedStatement) conn.prepareStatement(dateChoice);
       preparedStmt.setString    (1, t1);
       preparedStmt.setString    (2, t2);
       preparedStmt.setString    (3, id);
        // stmt = conn.createStatement();
        ResultSet rs = preparedStmt.executeQuery(dateChoice); 
        try {
                rs = preparedStmt.executeQuery(dateChoice);
                rs.next();
                rowCount = rs.getInt(1);
                System.out.println(rowCount);
            }
         catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        finally {
            rs.close();
            preparedStmt.close();
        }
        return rowCount; 

    }

如果不适合您，请分享确切的错误。

Answer 2

改变这个：

String dateChoice = "select count(*) " 
            + "from dancers " 
            + "where ts between (t1) and (t2)"
            + "and id = (id)"
            + "values (?)";

根据您使用的数据库语法。例如，如果您使用带有Mysql的Web服务器，请输入查询以查看拼写错误的位置。（如果你使用mysql，每个表需要dancers）

Answer 3

首先，您似乎已多次编辑此方法以尝试解决问题，这使其处于混乱状态。

从sql语句中删除“values（？）”，它不属于此处，似乎是从准备好的insert语句中遗留下来的。

调用带有零参数的preparedStmt.executeQuery（），你已经为它提供了sql字符串并且只将它命名为ONCE，你为rs赋值两次。

你的sql语句应该包含三个问号，试试

select count(*) from dancers where ts between ? and ? and id = ?

接下来调用prepareStmt.setString（）三次来提供值t1，t2和id。

另外，请记住在finally块中关闭连接对象。

使用变量创建SQL语句

3 个答案: