C# SQL Query – ExecuteNonQuery: Connection property has not been initialized

I have a number of blocks of code in my Windows Application that use the same structure to execute queries. After adding in a few new things to my code, these no longer work due to the error:

“ExecuteNonQuery: Connection property has not been initialized”

Blocks of code all look like this:

sc.Open();
cmd = new SqlCommand("UPDATE bin SET serialNumber=" + tb_computername.Text + " WHERE binNumber=" + binNumber);
cmd.ExecuteNonQuery();
sc.Close();
break;

The new code does this:

//Find Open BIN
int binNumber = 0;
int binIndex = 0;
string queryString = "SELECT * FROM bin";
SqlDataAdapter adapter = new SqlDataAdapter(queryString, scb);
DataSet binNumbers = new DataSet();
adapter.Fill(binNumbers, "bin");
for (int i = 0; i < 150; i++)
{
    binNumber++;                    
    if(binNumbers.Tables["bin"].Rows[binIndex]["serialNumber"].ToString() == "")
{
sc.Open();
cmd = new SqlCommand("UPDATE bin SET serialNumber=" + tb_computername.Text + " WHERE binNumber=" + binNumber);
cmd.ExecuteNonQuery();
sc.Close();
break;
}
binIndex++;

The connections for these are defined at the top of the class.

Answer

You need to assign it a SqlConnection object.

 cmd.Connection = connection;

Where connection is a SqlConnection object with your connection string etc.

Also for good practice you should wrap it in a using:

 using (SqlConnection connection = new SqlConnection("ConnectionString")) { 
     cmd.Connection = connection;
 } 

And paramerterized queries to prevent SQL Injection attacks.