救救我吧，实在搞不定，这方法哪错了？

Question

   var tb = SQLHelper.GetTable("select * from bjx_zt");    /// <summary>
    /// 返回指定Sql语句的DataTable
    /// </summary>
    /// <param name="strSql">传入的Sql语句</param>
    /// <returns>DataTable</returns>
    public static DataTable GetTable(string strSql)
    {
        SqlDataAdapter da = new SqlDataAdapter();
        DataTable datatable = new DataTable();
        try
        {
            using (SqlConnection connection = new SqlConnection(StrConn))
            {                using (SqlCommand cmd = new SqlCommand(strSql, connection))
                {
                    try
                    {
                        connection.Open();
                        cmd.CommandType = CommandType.Text;
                        da.SelectCommand = cmd;
                        da.Fill(datatable);
                    }
                    catch
                    {
                        connection.Close();
                    }
                }
            }
        }
        catch { }
        return datatable;
    }这怎么老返回空呢，
我表里有内容， 数据库链接也没错，求救大牛....

Answer 1

da.SelectCommand = cmd;
这这句话有问题，还是少写什么了...

Answer 2

SqlConnection conn = new SqlConnection(sqlConnectionString);
 
        conn.Open();
 
        SqlCommand cmd = new SqlCommand();
 
        cmd.Connection = conn;
 
        cmd.CommandType = CommandType.Text;
 
        cmd.CommandText = commandText;
 
        SqlDataAdapter da = new SqlDataAdapter(cmd); 
 
        DataSet ds = new DataSet();
 
        try
 
        {
 
            da.Fill(ds);
 
        }

Answer 3

 using (SqlConnection connection = new SqlConnection(StrConn))
            {                    try
                    {
                        da=new SqlDataAdapter(strSql, connection);
                        da.Fill(datatable);
                    }
                    catch
                    {
                        connection.Close();
                    }
                
            }
  

Answer 4

不好意思,搞错了  try
  {
  da=new SqlDataAdapter(strSql, StrConn);
  da.Fill(datatable);
  }
  catch
  {
  connection.Close();
  }
    
  

Answer 5

既然用了using了  还用try catch  多此一举

Answer 6

    /// <summary>
    /// 返回指定Sql语句的DataTable
    /// </summary>
    /// <param name="strSql">传入的Sql语句</param>
    /// <returns>DataTable</returns>
    public static DataTable GetTable(string strSql)
    {
        DataTable datatable = new DataTable();
        try
        {
            using (SqlConnection connection = new SqlConnection(StrConn))
            {
                  SqlDataAdapter adapter = new SqlDataAdapter(strSql,connection);
                  DataSet ds = new DataSet();
                  adapter.Fill(ds);
                  datatable  = ds.Tables[0];
            }
        }
        catch { }
        return ds;
    }

Answer 7

   /// <summary>
    /// 返回指定Sql语句的DataTable
    /// </summary>
    /// <param name="strSql">传入的Sql语句</param>
    /// <returns>DataTable</returns>
    public static DataTable GetTable(string strSql)
    {
        DataTable datatable = new DataTable();
        try
        {
            using (SqlDataAdapter adapter = new SqlDataAdapter(strSql,StrConn))
            {                  
                  DataSet ds = new DataSet();
                  adapter.Fill(ds);
                  datatable  = ds.Tables[0];
            }
        }
        catch { }
        return ds;
    }