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我正在将 JDBC 与 MySql 一起使用。我正在将数据插入一个表并获取其主键transactionid。现在将带有 transactionid 的数据插入到另一个表中。

我的代码：

if (connection != null) {
        System.out.println("Now connection is created successfully");
        stmt=connection.createStatement();
        Date date=new Date();
        DateFormat formatter = new SimpleDateFormat("dd/MM/yyyy hh:mm:ss");
        String time=formatter.format(date);
        System.out.println("time is   "+time);
        //insert transaction id and minimum support....
        mySql = "insert into Transaction (minimumsupport)   
 values('"+minimumSupport+"')";
        stmt.executeUpdate(mySql,Statement.RETURN_GENERATED_KEYS);
        ResultSet rt=stmt.getGeneratedKeys();
        int transactionId;
        while(rt.next()){
            transactionId=rt.getInt(1);
            System.out.println("the transaction id is: "+transactionId);
        }
        rt.close();

        int i;
        Statement stmt1;
        for(i=0;i<productArray.length;i++)
        {
            stmt=connection.createStatement();
            System.out.println("first value: "+productArray[i]);
            mySql = "insert into 
                      Producttransaction(transactionid,productId)
   values('"+transactionId+"','"+productArray[i]+"')";
            stmt.executeUpdate(mySql);
            status="productAdded";
            System.out.println("product added");
        }
            //To insert the data into the tables....
        connection.close();

引发以下异常：

Exception in thread "main" com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: 
Cannot add or update a child row: a foreign key constraint fails (`aprioridb`.`Producttransaction`, CONSTRAINT `fk_Productid` FOREIGN KEY (`transactionid`) REFERENCES `Product` (`productId`) ON DELETE NO ACTION ON UPDATE NO ACTION)
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1 回答 1

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看来您的外键约束是错误的：

FOREIGN KEY (transactionid) REFERENCES Product (productId)

应该

FOREIGN KEY (productid) REFERENCES Product (productId)

此外，了解预处理语句以避免 SQL 注入攻击，拥有更健壮和更高效的代码。

于 2013-04-04T14:53:16.087 回答