UC知道myreadr.reader()什么意思?
来源：百度知道 编辑：UC知道 时间：2024/05/22 11:45:39
Dim mycommand As New SqlCommand
Dim myreader As SqlDataReader
Dim ds As New DataSet
If DropDownList1.Text = "学生" Then
mycommand.Connection = myconnection
mycommand.Connection.Open()
mycommand.CommandType = CommandType.Text
mycommand.CommandText = "Select * From studentuser Where 学号='" & (TextBox1.Text).ToUpper & "' And 密码='" & (TextBox2.Text).ToUpper & "'"
myreader = mycommand.ExecuteReader
If myreader.Read() = True Then
myconnection.Close()
Session("aa") = TextBox1.Text
Server.Transfer("student.aspx")
Else
Dim myreader As SqlDataReader
Dim ds As New DataSet
If DropDownList1.Text = "学生" Then
mycommand.Connection = myconnection
mycommand.Connection.Open()
mycommand.CommandType = CommandType.Text
mycommand.CommandText = "Select * From studentuser Where 学号='" & (TextBox1.Text).ToUpper & "' And 密码='" & (TextBox2.Text).ToUpper & "'"
myreader = mycommand.ExecuteReader
If myreader.Read() = True Then
myconnection.Close()
Session("aa") = TextBox1.Text
Server.Transfer("student.aspx")
Else
DataReader的实例,获取下一条记录,存在(下一条记录)返回true,否则返回false
即 只有myreader.Read()后,才能获取下一条记录的字段内容
就是datareader的一个实例,一个myreadr.reader()表示从sql读取一次数据.
读取下一条记录,如果存在就为true.如果没记录了，就返回false