DataGrid view in asp.net is not displaying data

Answer 1

Well, I may misunderstand, but...you are not actually sending the string 'Label1.Text' I guess? You should send the value of the textbox, something like this (if you are building the SQL as a string?):

...[SQL]... + "c.customer_id = '"+ Label1.Text + "'" ...[rest of the SQL]

Answer 2

Use:
string.Format("c.customer_id = '{0}' and a.account_number = '{1}'", Label1.Text, Label2.Text);

Consider this query:
string query = "insert into TestTable (Column1, Column2) values (@p1, @p2)";

p1 & p2 are parameters, in order to set the value for the parameters you need to use:

queryParameters[0] = new SqlCeParameter("p1", SqlDbType.NVarChar);
queryParameters[0].Value = Label1.Text;
queryParameters[1] = new SqlCeParameter("p2", SqlDbType.NVarChar);
queryParameters[1].Value = Label2.Text;
SqlCeCommand command = new SqlCeCommand(query);
command.Parameters.AddRange(queryParameters);

When the wizard is generating the query you need to use place holders/parameters for customer_ID and account_number and set their values by using parameters.

Edit:
In order to make the wizard create a parameter to use in the query, add a ? in the filter column in the query builder wizard.