Question

我的代码错了，但这是我能想到的最接近解决方案的代码。我试图从1个表中为指定用户添加所有点，并将该值插入另一个表中。任何帮助表示赞赏。

这是我的代码：

Imports MySql.Data.MySqlClient
Public Class Leaderboard
Dim MysqlConn As MySqlConnection
Dim COMMAND As MySqlCommand
Private Sub submitBtn_Click(sender As Object, e As EventArgs) Handles    submitBtn.Click
    MysqlConn = New MySqlConnection
    MysqlConn.ConnectionString =
    "server=localhost;userid=root;password=root99;database=database"
    Dim READER As MySqlDataReader

    Try
        MysqlConn.Open()

        Dim Query As String
        Query = "  select (select SUM(Points) as sumpoints from database.progress where candidate_number_fk = '" & textbox_can.Text & "') (insert into database.leaderboard (username,points) values ('" & textbox_user.Text & "','  sumpoints '  )"
        COMMAND = New MySqlCommand(Query, MysqlConn)
        READER = Command.ExecuteReader
        MessageBox.Show("You have successfully submitted your score")

        MysqlConn.Close()
    Catch ex As MySqlException
        MessageBox.Show(ex.Message)
    Finally
        MysqlConn.Dispose()
    End Try
    My.Forms.Menu1.Show()
    Me.Hide()
End Sub

End Class

Answer 1

您不需要双重查询，因为您可以使用INSERT INTO .. SELECT FROM构造并在单个查询中完成它，例如

insert into database.leaderboard (username,points)
select 'Niam', SUM(Points) as sumpoints 
from database.progress 
where candidate_number_fk = '" & textbox_can.Text & "';

请注意，您正在使用字符串连接直接在查询中使用用户输入，这可能会导致 SQL注入。使用参数化查询而不是MySqlParameter类。

如何在vb中将从一个表中获得的值插入到另一个表中？

1 个答案: