How to call Table name from combo box in sql command

Question

I want to pool table name from the combo box in the SQL query. Below code, I use a static table name as "Logdata". For your reference, I attach the code.

 

Please guide me on how to call the selected table in the SQL query from the combo box.

 

Actually, I want to write the column name of the selected table in notepad.

public void getColumnName()
{
cmbFilterColumnName.Items.Clear();
SqlConnection columnCon = new SqlConnection(dbCon);
string columnQuery = @"Select Column_Name from information_Schema.Columns where Table_Name = 'Logdata'";
SqlCommand columnCmd = new SqlCommand(columnQuery, columnCon);
columnCon.Open();
SqlDataReader columnDr = columnCmd.ExecuteReader();
while (columnDr.Read())
{
string columnName = columnDr.GetString(0);
chkListBxColumnName.Items.Add(columnName);
}
columnCon.Close();
}