谁能帮我检查下这个数据连接又没用？

Question

我的数据链接代码是在一个CLass里面写的
 private string strConnection = string.Format("Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0}\\CommFuntion/DebetContrl.mdb", Application.StartupPath);
        private OleDbDataAdapter myAdapter;
        private DataSet myds;
        private DataTable mytb;
        private DataSet dss = new DataSet();
        OleDbConnection _SConn;
        public OleDbConnection SConn
        {
            get {
                _SConn = new OleDbConnection(strConnection);
            return _SConn; 
            }
            set { 
                _SConn = value; }
        }
        #region 打开关闭连接 Open(),Close()
        /// <summary>
        /// 打开数据库连接
        /// </summary>
        public void Open()
        {
            
            if (_SConn.State == ConnectionState.Closed)
                _SConn.Open();
        }        /// <summary>
        /// 关闭数据库连接
        /// </summary>
        public void Close()
        {
            if (_SConn.State == ConnectionState.Open)
            {
                _SConn.Close();
                //_SConn.Dispose();
            }
        }
        #endregion
而在这里引用
Func.SConn.Open();
            Func.Open();
            OleDbCommand cmd = new OleDbCommand("insert into Tb_Customerinfo(CID,CName,Csex,CStyle,CCAddress,"+
                "CPhone,CIDCard,CPost,CNetAddress,CEmail,BasicBankName,BasicBankNum,BankID,CAccountNum,"+
                "CCredit,CompanyName,CompanyChart,LicenseNum,Legal,LegalAddress,LegalPhone,LegalNum,Business,"+
                "RegMoney,Caddress,CoutrlerID)) values('" + textBox1.Text + "',"+
                "" + textBox2.Text + "," + Convert.ToString(Convert.ToInt32(comboBox3.SelectedIndex)) + ","+
                "" + Convert.ToString(Convert.ToInt32(comboBox1.SelectedIndex)) + "," + textBox4.Text + ","+
                "" + textBox6.Text + "," + textBox7.Text + "," + textBox8.Text + "," + textBox9.Text + ","+
                "" + textBox15.Text + "," + textBox10.Text + "," + textBox14.Text + ","+
                "" +  Convert.ToString(Convert.ToInt32(comboBox2.SelectedIndex) + 1) + ","+
                "" + textBox11.Text + "," + textBox13.Text + "," + textBox27.Text + ","+
                "" + Convert.ToString(Convert.ToInt32(comboBox5.SelectedIndex) + 1) + ","+
                "" + textBox24.Text + "," + textBox23.Text + "," + textBox22.Text + ","+
                "" + textBox20.Text + "," + textBox21.Text + "," + textBox3.Text + ","+
                "" + textBox17.Text + "," + textBox18.Text + "," + Convert.ToString(Convert.ToInt32(comboBox4.SelectedIndex) + 1)+ ")", Func.SConn);
            cmd.ExecuteNonQuery();
            Func.Close();
他老是提示 数据链接未打开，为什么啊，难道是我用的链接方式错了嘛？

Answer 1

哥们，你代码也乱了点吧！
在cmd 调用时，  "" + textBox17.Text + "," + textBox18.Text + "," + Convert.ToString(Convert.ToInt32(comboBox4.SelectedIndex) + 1)+ ")", Func.SConn);并没有打开数据连接！

Answer 2

从上面代码看，Open()方法时连接对象是否创建不可知道。应该在Open()方法中创建OleDbConnection对象。

Answer 3

设置断点，单步执行调试一下，看看open的时候是否正常

Answer 4

"" + textBox17.Text + "," + textBox18.Text + "," + Convert.ToString(Convert.ToInt32(comboBox4.SelectedIndex) + 1)+ ")", Func.SConn); 你又一次
Func.SConn
=>
           get { 
                _SConn = new OleDbConnection(strConnection); 
            return _SConn; 
            } 那不等于又返回一个新的连接，还是没打开的

Answer 5

            OleDbCommand cmd = new OleDbCommand("insert into Tb_Customerinfo(CID,CName,Csex,CStyle,CCAddress,"+ 
                "CPhone,CIDCard,CPost,CNetAddress,CEmail,BasicBankName,BasicBankNum,BankID,CAccountNum,"+ 
                "CCredit,CompanyName,CompanyChart,LicenseNum,Legal,LegalAddress,LegalPhone,LegalNum,Business,"+ 
                "RegMoney,Caddress,CoutrlerID)) values('" + textBox1.Text + "',"+ 
                "" + textBox2.Text + "," + Convert.ToString(Convert.ToInt32(comboBox3.SelectedIndex)) + ","+ 
                "" + Convert.ToString(Convert.ToInt32(comboBox1.SelectedIndex)) + "," + textBox4.Text + ","+ 
                "" + textBox6.Text + "," + textBox7.Text + "," + textBox8.Text + "," + textBox9.Text + ","+ 
                "" + textBox15.Text + "," + textBox10.Text + "," + textBox14.Text + ","+ 
                "" +  Convert.ToString(Convert.ToInt32(comboBox2.SelectedIndex) + 1) + ","+ 
                "" + textBox11.Text + "," + textBox13.Text + "," + textBox27.Text + ","+ 
                "" + Convert.ToString(Convert.ToInt32(comboBox5.SelectedIndex) + 1) + ","+ 
                "" + textBox24.Text + "," + textBox23.Text + "," + textBox22.Text + ","+ 
                "" + textBox20.Text + "," + textBox21.Text + "," + textBox3.Text + ","+ 
                "" + textBox17.Text + "," + textBox18.Text + "," + Convert.ToString(Convert.ToInt32(comboBox4.SelectedIndex) + 1)+ ")", Func.SConn);               Func.SConn.Open(); 
            cmd.ExecuteNonQuery();             Func.Close(); 看看。 

Answer 6

4楼的已经说了。
public OleDbConnection SConn 
        { 
            get { 
                _SConn = new OleDbConnection(strConnection); 
            return _SConn; 
            } 
            set { 
                _SConn = value; } 
        } 
你这个属性定义的也太狠了，访问一次属性，你就new一个连接……

Answer 7

public OleDbConnection SConn 
        { 
            get { 
                if（_SConn == null）
                   _SConn = new OleDbConnection(strConnection); 
            return _SConn; 
            } 
            set { 
                _SConn = value; } 
        } 

Answer 8

        public OleDbConnection SConn 
        { 
            get { 
                _SConn = new OleDbConnection(strConnection); 
            return _SConn; 
            } 
            set { 
                _SConn = value; } 
        } 
这里错了，这表示每一次使用Func.SConn都要实例化一次_SConn，连接当然就没有被Open了。
应把红色部分去掉。
要把这一部分写在类的构造方法中。。

Answer 9

搂主的上一贴：
http://topic.csdn.net/u/20081213/14/4c273fe5-49af-4b85-b159-6eff580ccc63.html
里面的数据连接类的代码只需要注释掉_SConn.Dispose(); 就可以了，怎么又把SConn这个属性给改了呢？

Answer 10

上面的已经说出答案了。还解释一下吧，
public OleDbConnection SConn
        {
            get {
                _SConn = new OleDbConnection(strConnection);
            return _SConn;
            }
            set {
                _SConn = value; }
        } 这个是问题的根本，Func.SConn.Open(); // 这里创建了链接 A
            Func.Open(); // 打开链接 A
            OleDbCommand cmd = new OleDbCommand("insert into Tb_Customerinfo(CID,CName,Csex,CStyle,CCAddress,"+
                "CPhone,CIDCard,CPost,CNetAddress,CEmail,BasicBankName,BasicBankNum,BankID,CAccountNum,"+
                "CCredit,CompanyName,CompanyChart,LicenseNum,Legal,LegalAddress,LegalPhone,LegalNum,Business,"+
                "RegMoney,Caddress,CoutrlerID)) values('" + textBox1.Text + "',"+
                "" + textBox2.Text + "," + Convert.ToString(Convert.ToInt32(comboBox3.SelectedIndex)) + ","+
                "" + Convert.ToString(Convert.ToInt32(comboBox1.SelectedIndex)) + "," + textBox4.Text + ","+
                "" + textBox6.Text + "," + textBox7.Text + "," + textBox8.Text + "," + textBox9.Text + ","+
                "" + textBox15.Text + "," + textBox10.Text + "," + textBox14.Text + ","+
                "" +  Convert.ToString(Convert.ToInt32(comboBox2.SelectedIndex) + 1) + ","+
                "" + textBox11.Text + "," + textBox13.Text + "," + textBox27.Text + ","+
                "" + Convert.ToString(Convert.ToInt32(comboBox5.SelectedIndex) + 1) + ","+
                "" + textBox24.Text + "," + textBox23.Text + "," + textBox22.Text + ","+
                "" + textBox20.Text + "," + textBox21.Text + "," + textBox3.Text + ","+
                "" + textBox17.Text + "," + textBox18.Text + "," + Convert.ToString(Convert.ToInt32(comboBox4.SelectedIndex) + 1)+ ")", Func.SConn); // 访问 SConn 又创建了一个新的对象 B，不同于A，而且默认是关闭的，
            cmd.ExecuteNonQuery();
            Func.Close(); 

Answer 11

  public void Open() 你Open的 只是 那个类里面的
  OleDbConnection _SConn; 
而你get的的时候 
        public OleDbConnection SConn
        {
            get {
                _SConn = new OleDbConnection(strConnection);
            return _SConn;
            }
            set {
                _SConn = value; }
        } 
这个  只是 返回一个新的实例对象  
你的 
而在这里引用
Func.SConn.Open();
            Func.Open();
            OleDbCommand cmd = new OleDbCommand("insert into Tb_Customerinfo(CID,CName,Csex,CStyle,CCAddress,"+
                "CPhone,CIDCard,CPost,CNetAddress,CEmail,BasicBankName,BasicBankNum,BankID,CAccountNum,"+
                "CCredit,CompanyName,CompanyChart,LicenseNum,Legal,LegalAddress,LegalPhone,LegalNum,Business,"+
                "RegMoney,Caddress,CoutrlerID)) values('" + textBox1.Text + "',"+
                "" + textBox2.Text + "," + Convert.ToString(Convert.ToInt32(comboBox3.SelectedIndex)) + ","+
                "" + Convert.ToString(Convert.ToInt32(comboBox1.SelectedIndex)) + "," + textBox4.Text + ","+
                "" + textBox6.Text + "," + textBox7.Text + "," + textBox8.Text + "," + textBox9.Text + ","+
                "" + textBox15.Text + "," + textBox10.Text + "," + textBox14.Text + ","+
                "" +  Convert.ToString(Convert.ToInt32(comboBox2.SelectedIndex) + 1) + ","+
                "" + textBox11.Text + "," + textBox13.Text + "," + textBox27.Text + ","+
                "" + Convert.ToString(Convert.ToInt32(comboBox5.SelectedIndex) + 1) + ","+
                "" + textBox24.Text + "," + textBox23.Text + "," + textBox22.Text + ","+
                "" + textBox20.Text + "," + textBox21.Text + "," + textBox3.Text + ","+
                "" + textBox17.Text + "," + textBox18.Text + "," + Convert.ToString(Convert.ToInt32(comboBox4.SelectedIndex) + 1)+ ")", Func.SConn);
            cmd.ExecuteNonQuery();
            Func.Close(); 
这个代码 
可以修改下 
OleDbConnection MyConn;
MyConn=Func.SConnMyConn.Open();
然后  用MyConn 代替你里面的那些 Func的操作，应该就可以了