Question

They have relation between AuthorID and AID

I want to add attributes to 2 tables at the same time

'Cannot add or update a child row: a foreign key constraint fails (bibliographydb10.book, CONSTRAINT book_ibfk_1 FOREIGN KEY (AuthorID) REFERENCES author (AID))'

public static bool AddNewPackage(BookCitation package)
    {
        MySqlConnection connection = DataAccess.getConnection();

        string insertStatement =
            @"INSERT into Book (
                AuthorName,
                PubYear, 
                BookTitle, 
                PubCity,
                PubName,
                PageNumbers) 
                VALUES (
                @AuthorName,
                @PubYear, 
                @BookTitle, 
                @PubCity,
                @PubName,
                @PageNumbers);
                INSERT into Author (
                AID,
                AuthorNamee,
                Affiliation)
                VALUES (@AID, @AuthorNamee, @Affiliation)";
        MySqlCommand insertCommand = new MySqlCommand(insertStatement, connection);
        insertCommand.Parameters.AddWithValue("@AID", package.AID);
        insertCommand.Parameters.AddWithValue("@AuthorName", package.AuthorName);
        insertCommand.Parameters.AddWithValue("@AuthorNamee", package.AuthorNamee);
        insertCommand.Parameters.AddWithValue("@Affiliation", package.Affiliation);
        insertCommand.Parameters.AddWithValue("@PubYear", package.PublishYear);
        insertCommand.Parameters.AddWithValue("@BookTitle", package.BookTitle);
        insertCommand.Parameters.AddWithValue("@PubCity", package.PublisherCity);
        insertCommand.Parameters.AddWithValue("@PubName", package.Publisher);
        insertCommand.Parameters.AddWithValue("@PageNumbers", package.PageNumbers);

        try
        {
            connection.Open();
            insertCommand.ExecuteNonQuery();
            return true;
        }
        catch (SqlException ex)
        {
            MessageBox.Show(ex.GetType() + ex.Message);
            return false;
        }
        finally
        {
            connection.Close();
        }

    }

public class BookCitation
{
    public int BookCID { get; set; }
    public int AID { get; set; }
    public string AuthorName { get; set; }
    public string AuthorNamee { get; set; }
    public string Affiliation { get; set; }
    public DateTime PublishYear { get; set; }
    public string BookTitle { get; set; }
    public string PublisherCity { get; set; }
    public string Publisher { get; set; }
    public string PageNumbers { get; set; }
}

如何使用外键添加AuthorID？

Answer 1

该错误消息表示作者必须首先存在。插入新作者，检索该新作者的AID，然后插入新书，并将该书的AID列设置为与您刚刚插入的新作者的检索AID值相同的值

为什么外键在C＃和MySql之间不起作用？

1 个答案: