MYSQL VB.NET 我想知道如何只显示重复的记录

Question

我想只显示重复的行，并删除 GridView 中的所有单行（非重复）

我的代码是：

 Private Sub load_table()
    MysqlConn = New MySqlConnection
    MysqlConn.ConnectionString = "server=localhost;userid=root;password=nassa640088;database=testing"
    Dim SDA As New MySqlDataAdapter
    Dim dbDataSet As New DataTable
    Dim bSource As New BindingSource

    Try
        MysqlConn.Open()
        Dim Query As String
        Query = "select * from testing.login"
        COMMAND = New MySqlCommand(Query, MysqlConn)
        SDA.SelectCommand = COMMAND
        SDA.Fill(dbDataSet)
        bSource.DataSource = dbDataSet
        DataGridView1.DataSource = bSource
        SDA.Update(dbDataSet)



        MysqlConn.Close()
    Catch ex As MySqlException
        MessageBox.Show(ex.Message)
    Finally
        MysqlConn.Dispose()

    End Try

End Sub

Answer 1

在这种情况下，使用group by 更改您的查询（假设有一个id 列）

select * from testing.login where id in (
select id 
from testing.login
group by id
having count(id) > 1 );