如何正确初始化 .NET OleDbConnection 对象及其 ConnectionString 属性？

Question

这是我用于连接和使用 Access 数据库的 C# 代码。

using System.Data.OleDb;

var cb = new OleDbCommandBuilder(da);

DataRow dRow = ds1.Tables["Customer"].NewRow();

dRow[0] = textBox1.Text;
dRow[1] = textBox2.Text;
dRow[2] = textBox3.Text;

ds1.Tables["Customer"].Rows.Add(dRow);

da.Update(ds1, "Customer");

con.Close();

MessageBox.Show("Entry added");

但是 da.Update(ds1,"Customer"); 行抛出异常：

ConnectionString 属性尚未初始化。

Answer 1

我不太明白你的问题，但这里有一些示例代码可以帮助你弄清楚你想要做什么。

为了清楚起见：数据库名为“MyDb.accdb”，并有一个名为“Customer”的表，其中包含两个字段“Name”和“Phone”。此示例假设数据库与可执行文件位于同一目录中。

private void AddCustomer(string customerName, string customerPhone)
{
    string name = customerName;
    string phone = customerPhone;

    // An easy way to determine the connection string to your database is to open the database from Visual Studio's 'Server Explorer'.
    // Then, from Server Explorer, view the Properties of the database - in the Properties you will see the "Connection String". 
    // You can/should replace the arbitrary part of the path with "|DataDirectory|".
    string connString = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|MyDb.accdb;Persist Security Info=True";

    // Create your sql query in a string variable
    string cmdText = string.Format("INSERT INTO Customer(Name, Phone) VALUES('{0}','{1}');", name, phone);

    // Use the 'using' statement on your connection so that the resource is managed properly
    using (System.Data.OleDb.OleDbConnection connection = new System.Data.OleDb.OleDbConnection(connString))
    {                
        // Here's where/how we fire off the INSERT statement
        OleDbCommand cmd = new OleDbCommand(cmdText, connection);
        connection.Open();
        cmd.ExecuteNonQuery();
    }
}