在VB.NET中检查SQL结果 [英] Checking for an SQL result in VB.NET

问题描述

我需要检查我的SQL语句是否从我用来存储数据的Access数据库中返回了任何结果.

I need to check if my SQL statement returned any results from the Access db I'm using to store my data.

我有此代码atm:

        cn = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; Data Source=D:\Computing Project\database.mdb;")
        cn.Open()
        cmd = New OleDbCommand("SELECT * FROM(" & roomvar.ToLower() & ") WHERE (((" & roomvar.ToLower() & ".date)=" & Chr(34) & dtpDate.Value.Date & Chr(34) & "))", cn)
        dr = cmd.ExecuteReader
            While dr.Read()

            End While
        End If
        dr.Close()

我希望能够检查(可能是通过布尔值或其他方式)此结果返回了查询.我正在使用VB.net.

I would like to be able to check (maybe via a boolean value or something) that this result returned a query. I'm using VB.net.

谢谢

推荐答案

简单.使用 OleDbDataReader.HasRows 属性调用ExecuteReader之后.

Simple. Use the OleDbDataReader.HasRows Property after your call to ExecuteReader.

    cn = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; Data Source=D:\Computing Project\database.mdb;")
    cn.Open()
    cmd = New OleDbCommand("SELECT * FROM(" & roomvar.ToLower() & ") WHERE (((" & roomvar.ToLower() & ".date)=" & Chr(34) & dtpDate.Value.Date & Chr(34) & "))", cn)
    dr = cmd.ExecuteReader

    hasRows = dr.HasRows

    dr.Close()

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