Question

ExecuteNonQuery: Connection 属性尚未初始化。

private void button2_Click(object sender, EventArgs e)
{
String strConn1 = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Application.StartupPath + "\\member.mdb";
OleDbConnection conn1 = new OleDbConnection(strConn1);
OleDbDataAdapter oleDbDataAdapter1 = new OleDbDataAdapter("select * from Users",conn1);
string userName = txtName.Text.Trim();
string sql = "select count(*)from Users where UserName='" + userName + "'";
conn1.Open();
OleDbCommand cmd = new OleDbCommand(sql, conn1);
int n = (int)cmd.ExecuteScalar();
if (n > 0)
{
MessageBox.Show("用户已存在");
return;
}
else
{

OleDbCommand cmd2 = new OleDbCommand ();

cmd2.CommandText = "insert into Users " + "(UserName,Sex,Password,RealName,Email,Question,Answer)" + "values (@UserName,@Sex@Password,@RealName,@Email,@Question,@Answer)";

cmd2.Parameters.Add("@UserName", OleDbType.Char, 6, "UserName");
cmd2.Parameters.Add("@Sex", OleDbType.Char, 2, "Sex");
cmd2.Parameters.Add("@RealName", OleDbType.Char, 6, "RealName");
cmd2.Parameters.Add("@Password", OleDbType.Char, 6, "Password");
cmd2.Parameters.Add("@Question", OleDbType.Char, 6, "Question");

cmd2.Parameters.Add("@Email", OleDbType.Char, 20, "Email");
cmd2.Parameters.Add("@Answer", OleDbType.Char, 10, "Answer");
cmd2.Parameters["@UserName"].Value = txtName.Text;
cmd2.Parameters["@Sex"].Value = checkedListBox1.Text;
cmd2.Parameters["@RealName"].Value = txtRealName.Text;
cmd2.Parameters["@Password"].Value = txtPwd1.Text;
cmd2.Parameters["@Question"].Value = comboBox1.Text;
cmd2.Parameters["@Email"].Value = txtEmail.Text;
cmd2.Parameters["@Answer"].Value = txtAnswer.Text;
cmd2.ExecuteNonQuery();
DataSet dataSet11 = new DataSet();
oleDbDataAdapter1.Fill(dataSet11, "Users");
conn1.Close();

555555555怎么改

Answer 1

OleDbCommand cmd2 = new OleDbCommand ();
你只是把cmd2初始化了，但是没有指定它的连接啊！

你看，你初始化cmd的时候，就为他指定了 conn1 这个数据库连接。。
OleDbCommand cmd = new OleDbCommand(sql, conn1);

Answer 2

一楼正解,cmd2没有指定Connection

Answer 3

cmd2 New的时候没有给他conn参数啊
要么cmd2.connection=……；
要么就OleDbCommand cmd2=New OleDbCommand(text,conn1)

Answer 4

connection
换一个变量名。
报错原因是没有初始化，就是说
没有连接上。
看一下数据库服务是否开启，数据库连接语句是否出错。

Answer 5

这就说明的连接代码有问题，不能正确连接到数据库。