Android 如何在mysql数据库中更新查询

我正在尝试用以下代码更新mysql数据库 当我运行该程序时，控制台中出现以下错误

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错误：

You have an error in your SQL syntax; check the manual that corresponds to your MySQL
server version for the right syntax to use near 
'SET AVG_COST = 100000 , RWDS_INCENT = 200 , OTH_EXPENSES = 10000 , 
TRAVELLING_EX' at line 1

        Class.forName("com.mysql.jdbc.Driver");
        Connection con = DriverManager.getConnection(DB_URL,"root","root");
        System.out.println("Remote DB connection established");
        PreparedStatement statement=con.prepareStatement("UPDATE TBL_MONTHLY_EXPENSES_DETAILS  " +
                "SET AVG_COST = "+AVG_COST+" ," +
                   " RWDS_INCENT = "+RWDS_INCENT +" ,"+
                   " OTH_EXPENSES = "+OTH_EXPENSES+" ,"+
                   " TRAVELLING_EXPENSES = "+TRAVELLING_EXPENSES+" ,"+
                   " CLIENT_VISITS = "+CLIENT_VISITS+" ,"+
                   " REV_RECD = "+REV_RECD+" "
                +" WHERE PJT_CODE = '"+PJT_CODE
                +"' AND PJT_MONTH = '"+PJT_MONTH
                +"' AND PJT_YEAR = '"+PJT_YEAR+"' "
                );
        statement.executeUpdate();

代码：

You have an error in your SQL syntax; check the manual that corresponds to your MySQL
server version for the right syntax to use near 
'SET AVG_COST = 100000 , RWDS_INCENT = 200 , OTH_EXPENSES = 10000 , 
TRAVELLING_EX' at line 1

        Class.forName("com.mysql.jdbc.Driver");
        Connection con = DriverManager.getConnection(DB_URL,"root","root");
        System.out.println("Remote DB connection established");
        PreparedStatement statement=con.prepareStatement("UPDATE TBL_MONTHLY_EXPENSES_DETAILS  " +
                "SET AVG_COST = "+AVG_COST+" ," +
                   " RWDS_INCENT = "+RWDS_INCENT +" ,"+
                   " OTH_EXPENSES = "+OTH_EXPENSES+" ,"+
                   " TRAVELLING_EXPENSES = "+TRAVELLING_EXPENSES+" ,"+
                   " CLIENT_VISITS = "+CLIENT_VISITS+" ,"+
                   " REV_RECD = "+REV_RECD+" "
                +" WHERE PJT_CODE = '"+PJT_CODE
                +"' AND PJT_MONTH = '"+PJT_MONTH
                +"' AND PJT_YEAR = '"+PJT_YEAR+"' "
                );
        statement.executeUpdate();

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差旅费可能有问题。检查您试图更新的值。
我还想知道在mysql数据库中插入相同值的查询。我想在mysql中插入与上述相同的数据（更新查询）。在更新查询中要修改哪些内容？行：
插入TBL\u每月费用详细信息（平均成本、RWD费用）值（1、2）
。自己添加更多的列和值，您应该遵循这个模式。