Question

我做了一个小应用程序，它读入了Excel文件。我将它连接到我的MySQL数据库，以便我可以将文件放入包含多个表的数据库中。但是，在将值应用到“订单”中时表，有一个SQLException，值不进入数据库。这是CustomerMC类中的例外。＆＃39;客户＆＃39;的价值观。 table进入数据库。

我所拥有的代码包含一个main，我读取文件并生成Customer和Order的实例，两个容器类，其中包含值，一个与此无关的连接类，以及一个Customer类的Customer查询所在的位置。

主：

public static void main(String[] args){
    CustomerMC cmc = new CustomerMC();
    ArrayList<Customer> customers = new ArrayList<>();
    ArrayList<Order> orders = new ArrayList<>();

    try {
        try (FileInputStream file = new FileInputStream(new File("C:/Users/Wout/Desktop/ProjectTest.xlsx"))) {
            XSSFWorkbook wb = new XSSFWorkbook(file);
            XSSFSheet sh = wb.getSheetAt(0);

            Iterator<Row> rowIterator = sh.iterator();
            while(rowIterator.hasNext()) {

                Row row = rowIterator.next();
                Iterator<Cell> cellIterator = row.cellIterator();

                int counter = 0;
                int cid = 0;
                int OrderID = 0;
                String name = "";
                String purchase = "";
                String age = "";
                String product = "";

                while (cellIterator.hasNext() && row.getRowNum() != 0) {
                    Cell cell = cellIterator.next();
                    counter++;

                    switch (counter) {
                        case 1:
                            cid = (int)cell.getNumericCellValue();
                            break;
                        case 2:
                            name = cell.getStringCellValue();
                            break;
                        case 3:
                            purchase = cell.getStringCellValue();
                            break;
                        case 4:
                            age = "" + cell.getNumericCellValue();
                            break;
                        case 5:
                            OrderID = (int)cell.getNumericCellValue();
                            break;
                        case 6:
                            product =  "" + cell.getStringCellValue();
                            break;
                        case 7:
                            cid = (int)cell.getNumericCellValue();
                            break;
                    }
                }
                if(row.getRowNum() != 0) {
                    Customer customer = new Customer(cid,name,purchase,age);
                    Order order = new Order(OrderID, product, cid);
                    customers.add(customer);
                    orders.add(order);
                }


            }
        }
    } catch (FileNotFoundException ex) {
        System.out.println("File has not been found");
    } catch (IOException ex) {
        System.out.println("IOException");
    }

    for(Order order : orders) {
        System.out.println(order.toString());
        cmc.insertOrder(""+order.getOrderid(), order.getProduct(), ""+order.getCid());
    }

    for(Customer customer : customers){
         System.out.println(customer.toString());
         cmc.insertCustomer(""+customer.getCid(), customer.getName(), customer.getPurchase(), customer.getAge());          
    }


}

容器类：

public class Customer {
private int cid;
private String name;
private String purchase;
private String age;

public Customer(int cid, String name, String purchase, String age) {
    this.cid = cid;
    this.name = name;
    this.purchase = purchase;
    this.age = age;
}

public int getCid() {
    return cid;
}

public void setCid(int cid) {
    this.cid = cid;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getPurchase() {
    return purchase;
}

public void setPurchase(String purchase) {
    this.purchase = purchase;
}

public String getAge() {
    return age;
}

public void setAge(String age) {
    this.age = age;
}

@Override
public String toString() {
    return "" + cid + " ; "+ name + " ; " + purchase + " ; " + age;
}

public class Order {
private int orderid;
private String product;
private int cid;

public Order(int orderid, String product, int cid) {
    this.orderid = orderid;
    this.product = product;
    this.cid = cid;
}

public int getOrderid() {
    return orderid;
}

public void setOrderid(int orderid) {
    this.orderid = orderid;
}

public String getProduct() {
    return product;
}

public void setProduct(String product) {
    this.product = product;
}

public int getCid() {
    return cid;
}

public void setCid(int cid) {
    this.cid = cid;
}

@Override
public String toString() {
    return "" + orderid + " ; " + product + " ; " + cid;
}

客户模型类：

public class CustomerMC {
private Connection connection;
private PreparedStatement pst;
String query;
ResultSet rs;

public CustomerMC(){
    try{
       connection = SimpleDataSourceV2.getConnection(); 
    }
    catch(SQLException e){
        System.out.println("Connection failure");
        e.printStackTrace();
    }
}

public String insertCustomer(String cid, String name, String purchase, String age) {
    String returning = null;
    try {
        query = "insert into CustomerService values(?,?,?,?);";

        pst = connection.prepareStatement(query);
        pst.setInt(1, Integer.parseInt(cid));
        pst.setString(2, name);
        pst.setString(3, purchase);
        pst.setString(4, age);

        int response = pst.executeUpdate();
        returning = response +" Records has/have been edited";

    } catch (SQLException e) {
        returning = "An error has occured";
        System.out.println(returning);

    }

    return returning;

}
public String insertOrder(String orderid, String product, String id) {
    String returning = null;
    try {
        query = "insert into CustomerService values(?,?,?,?);";

        pst = connection.prepareStatement(query);
        pst.setInt(1, Integer.parseInt(orderid));
        pst.setString(2, product);
        pst.setInt(3, Integer.parseInt(id));

        int response = pst.executeUpdate();
        returning = response +" Records has/have been edited";

    } catch (SQLException e) {
        returning = "xx";
        System.out.println(returning);

    }

    return returning;

}

显然还有一个类与数据库连接。这与这个问题无关，所以我决定不予考虑。

然后我的Excel表格是一张简单的表格，其中cid，名称，购买者和年龄是＆＃39;客户＆＃39; table和OrderID，Product和cid是＆＃39; Orders＆＃39;表。订单中的Cid是客户的外键。 Excel会自动生成该字段，作为在customers表中获取的值。我重新实现了cid值，使自己更容易。

表：https://prnt.sc/ff1yd0

运行后我得到的输出如下：

    1 ; Monitor ; 1
    java.sql.SQLException: Column count doesn't match value count at row 1
    2 ; Couch ; 2
    3 ; Appartment ; 3
        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1074)
        at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4120)
        at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4052)
        at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2503)
        at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2664)
        at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2794)
        at 
    com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2155)
        at 
     com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2458)
        at 
    com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2375)
        at 
    com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2359)
        at p4project.CustomerMC.insertOrder(CustomerMC.java:66)
        at p4project.Main.main(Main.java:103)
    java.sql.SQLException: Column count doesn't match value count at row 1

    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1074)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4120)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4052)
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2503)

我不知道为什么第二张桌子没有实施，我希望有人可以提供帮助！任何帮助表示赞赏。

Answer 1

您的例外情况是：CustomerMC.insertOrder(CustomerMC.java:66)并且说 java.sql.SQLException: Column count doesn't match value count。

您的CustomerService表似乎有7列，但您想插入只有4个值的行。这是不可能的。您必须为每列提供一个值（如果您没有指定要插入值的列的名称）。如果您的架构允许，您也可以插入空值，但您必须指定它。该语句不知道您希望将哪些列留空。

如何阅读Excel工作表的一部分，而不是整篇Java？

1 个答案: