private void button1_Click(object sender, EventArgs e)
{
List<float> dataa = new List<float>(16);
List<float> datab = new List<float>(16);
SqlConnection conn=new SqlConnection (@"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Data\dss.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True");
conn.Open();
SqlCommand cmd = new SqlCommand("select * from cbyc",conn);
SqlDataReader reader = cmd.ExecuteReader();
while (reader.Read())
{
dataa.Add((float)reader["X"]);
datab.Add ((float)reader["Y"]);
}
}
如上代码,cbyc表的定义是int ID, float X,float Y,就这三列,为什么我添加到LIST数组里,然后点击按钮,总是提示指定的转换无效??为什么啊我觉得没错啊。。
{
List<float> dataa = new List<float>(16);
List<float> datab = new List<float>(16);
SqlConnection conn=new SqlConnection (@"Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Data\dss.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True");
conn.Open();
SqlCommand cmd = new SqlCommand("select * from cbyc",conn);
SqlDataReader reader = cmd.ExecuteReader();
while (reader.Read())
{
dataa.Add((float)reader["X"]);
datab.Add ((float)reader["Y"]);
}
}
如上代码,cbyc表的定义是int ID, float X,float Y,就这三列,为什么我添加到LIST数组里,然后点击按钮,总是提示指定的转换无效??为什么啊我觉得没错啊。。
{
dataa.Add(reader["X"]==null?0:Convert.ToSingle(reader["X"]));
datab.Add (reader["X"]==null?0:Convert.ToSingle(reader["Y"]));
}
reader["X"]==DBNull.Value?0:Convert.ToSingle(reader["X"]);