如何初始化阅读器 [英] How do I initialise the reader

问题描述

 Dim ConnectionString As String =Data Source =（LocalDB）\ MSSQLLocalDB
 Dim Connection As New SqlConnection（ConnectionString）
 Connection。 Open（）
 Dim命令为新SqlCommand（SELECT * FROM Table）
 Dim Reader As SqlDataReader 
 Reader = Command.ExecuteReader（）
 Dim DT As New DataTable（） 
 DT.Load（读者）
 Connection.Close（）
 ReservationsDVG.DataSource = DT 
 

这会引发异常错误，说明读者尚未初始化

解决方案

链接连接到命令...当前命令不知道关于帽子连接执行查询，所以没有读者创建...

 Commnad.Connection = Connection 
 Reader = Command.ExecuteReader（）

Dim ConnectionString As String = "Data Source= (LocalDB)\MSSQLLocalDB"
Dim Connection As New SqlConnection(ConnectionString)
Connection.Open()
Dim Command As New SqlCommand("SELECT * FROM Table")
Dim Reader As SqlDataReader
Reader = Command.ExecuteReader()
Dim DT As New DataTable()
DT.Load(Reader)
Connection.Close()
ReservationsDVG.DataSource = DT

This throws an exception error saying that reader hasn't been initialised

解决方案

Link Connection to Command...Currently Command does not know on hat connection to execute the query, so no reader created...

Commnad.Connection = Connection
Reader = Command.ExecuteReader()

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