我不知道这段代码的错误在哪里

Question

尝试

MySqlConn.Open()

        Dim Query = "Select * From venuesdb.cost where EventDate  >= ('" & DateTimePicker1.Text & "') AND =< ('" & DateTimePicker2.Text & "')"
        Command = New MySqlCommand(Query, MySqlConn)
        SQLDataAdapter.SelectCommand = Command
        SQLDataAdapter.Fill(DatabaseDatSet)
        Bindsource.DataSource = DatabaseDatSet
        DataGridView1.DataSource = Bindsource
        SQLDataAdapter.Update(DatabaseDatSet)
        MySqlConn.Close()

    Catch ex As Exception
        MessageBox.Show(ex.Message)

    End Try
    MySqlConn.Dispose()

我一直收到错误消息，说这里有一个 SQL 错误 '>= ('" & DateTimePicker2 & " ')'

Answer 1

您的语法不正确，您可以使用不带 <= 的 between 和 >=（注意运算符中的符号顺序）：

Dim Query = "select *
             from venuesdb.cost
             where EventDate  between '" & DateTimePicker1.Text & "' AND '" & DateTimePicker2.Text & "'"

或每次指定条件时指定字段：

Dim Query = "select *
             from venuesdb.cost
             where EventDate  >= '" & DateTimePicker1.Text & "' AND EventDate <= '" & DateTimePicker2.Text & "'"

Answer 2

您在查询中遗漏了一个 EventDate。将您的代码更改为：

Dim Query = "Select * From venuesdb.cost where EventDate  >= ('" & DateTimePicker1.Text & "') AND EventDate =< ('" & DateTimePicker2.Text & "')"

此外，您应该在查询中使用参数以避免 SQL 注入攻击。您可以在 this SO 问题中阅读更多相关信息。