C# 从从 Access 数据库读取的 OleDbDataReader 取回值
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Getting values back from OleDbDataReader reading from Access database
提问by NealR
Below it the code I'm using to connect to an Access database and pull the values from the query. Problem is.. I cannot get any values back from the reader object. I can see that there are the correct amount of rows, however I keep getting an InvalidOperationException (whether I use GetValue() or GetString()) saying "No data exists for the row/column."
在它下面是我用来连接到 Access 数据库并从查询中提取值的代码。问题是.. 我无法从读取器对象中取回任何值。我可以看到有正确的行数，但是我不断收到 InvalidOperationException（无论我使用 GetValue() 还是 GetString()），说“行/列不存在数据”。
System.Data.OleDb.OleDbConnection conn = new
System.Data.OleDb.OleDbConnection();
conn.ConnectionString = @"Provider=Microsoft Office 12.0 Access Database Engine OLE DB Provider;" +
@"Data source= C:\Users\nearod\Desktop\ImportDB.accdb";
try
{
conn.Open();
OleDbCommand cmd = new OleDbCommand("SELECT * FROM [SQL Agent Unique ID Test Load]", conn);
OleDbDataReader reader = cmd.ExecuteReader();
string companyCode = reader.GetValue(0).ToString();
string agentId = reader.GetString(1);
string firstName = reader.GetString(2);
string lastName = reader.GetString(3);
string nameSuffix = reader.GetString(4);
string corporateName = reader.GetString(5);
string entityType = reader.GetString(6);
string obfSSN = reader.GetString(7);
string obfFEIN = reader.GetString(8);
string dummyIndicator = reader.GetString(9);
// Insert code to process data.
}
catch (Exception ex)
{
MessageBox.Show("Failed to connect to data source");
}
finally
{
conn.Close();
}
采纳答案by Hassan Boutougha
you have to call Read method like below (use using instead of disposing yourself connection
您必须调用如下所示的 Read 方法（使用 using 而不是处理自己的连接
string connectionString = @"Provider=Microsoft Office 12.0 Access Database Engine OLE DB Provider;" + @"Data source= C:\Users\nearod\Desktop\ImportDB.accdb";
string queryString= "SELECT * FROM [SQL Agent Unique ID Test Load]";
try
{
using (OleDbConnection connection = new OleDbConnection(connectionString))
{
OleDbCommand command = new OleDbCommand(queryString, connection);
connection.Open();
OleDbDataReader reader = command.ExecuteReader();
while (reader.Read())
{
string companyCode = reader.GetValue(0).ToString();
string agentId = reader.GetString(1);
string firstName = reader.GetString(2);
string lastName = reader.GetString(3);
string nameSuffix = reader.GetString(4);
string corporateName = reader.GetString(5);
string entityType = reader.GetString(6);
string obfSSN = reader.GetString(7);
string obfFEIN = reader.GetString(8);
string dummyIndicator = reader.GetString(9);
// Insert code to process data.
}
reader.Close();
}
}
catch (Exception ex)
{
MessageBox.Show("Failed to connect to data source");
}
回答by CSharpDev
Modify your code like this:
像这样修改你的代码：
using (OleDbConnection connection = new OleDbConnection(connectionString))
{
OleDbCommand command = new OleDbCommand(queryString, connection);
connection.Open();
using (OleDbDataReader reader = command.ExecuteReader())
{
while (reader.Read())
{
string companyCode = reader.GetValue(0).ToString();
string agentId = reader.GetString(1);
string firstName = reader.GetString(2);
string lastName = reader.GetString(3);
string nameSuffix = reader.GetString(4);
string corporateName = reader.GetString(5);
string entityType = reader.GetString(6);
string obfSSN = reader.GetString(7);
string obfFEIN = reader.GetString(8);
string dummyIndicator = reader.GetString(9);
// Insert code to process data.
}
}
}
