Is the repeating table you want to load the data into in your main data source? Is your form bound to the database (that is, did you base your form off the database when you created it)?
If your form is not bound to the database, and you are using built in InfoPath SQL data connections to get this data back, without writing code your only option would be to return all the data. If you don't need the data in the main data source of your form, you can just display a repeating table bound to that secondary data source and use conditional formatting to hide the rows that don't match the account number entered in the form.
If you do need the data copied into the main data source of your form and you are using IP 2007, you might want to give qRules a try -- it has a Copy Table command you can use for this.