将数据从Access DB填充到vb.net数据集

问题描述

大家好，

我有问题.

状况:
我已经声明了一个字符串来保存查询中的数据

Hi all,

I have a problem.

Situation:
I have declared a string to hold the data from a query

strSQL=GetPayment(strDateFrm,strDateTo)
cnCMD = New OleDbCommand(strSQL, cnDB)
cnCMD.CommandType = CommandType.Text
rdr = cnCMD.ExecuteReader
If Not (IsNothing(strSQL)) Then
                        If rdr.Read Then  -------> "problem occurs here"
                            While rdr.Read

我想问一个能解决我问题的人:
如果数据库中的数据为空，该怎么办?因为当数据库中不存在数据时，它将填充为DataSet的空白，并且DataReader将找不到任何内容，并跳过我在数据库中没有输入条件的步骤，它将填充"-NA-"字符串值. br/>
或者谁能​​告诉我将数据库中的数据插入到DataSet的其他代码.
我对在搜索引擎中找到的答案感到困惑，因为大多数情况下，它们会将数据放入ListView，DataGridView之类的文件中.
这让我感到困惑.

我使用对象objPayment作为介质从数据库检索数据并填写DataSet列.
例如:

I want to ask anyone who can solve me for:
If data from database is empty, what should I do? Because when data is not exist in database, it will fill empty to DataSet and DataReader will find nothing and skip the step where I put a condition if nothing in database, it will fill "-NA-" string value.

Or can anyone tell me the other code for inserting data from database to DataSet.
I''m confused about the answer that I found in search engine because mostly they put the data into something such as ListView, DataGridView.
It confuses me.

I use an object objPayment as medium to retrieve data from database and fill in DataSet column.
For example:

If Not (IsDBNull(rdr("intMPAJRecpNo"))) Then
         objChqDataRow.strReceiptNo = rdr("intMPAJRecpNo")
Else
         objChqDataRow.strReceiptNo = "- NA -"
End If

如果有人无法使用DataReader处理数据，请帮忙.

If someone has the other way from my way to manipulate data from using DataReader, kindly help me.

推荐答案

While rdr.HasRows ANDALSO rdr.Read
'... code ...
End While

如果您这样做:

If you do this:

If rdr.Read Then
    While rdr.Read

您实际上是在两次调用.Read时跳过了一行(在IF上再次输入WHILE).

You are actually skipping a row as you are calling .Read twice (Once on IF and again entering your WHILE).

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