SQL Query

I have two tables that joines them by project_no. Following are two tables with its values. TABLE A TABLE B ----------------------- project_no project_no ________________________ 1 1 2 - 3 3 When I user outer join then it says that it found 3 rows which is correct. But is there anyway I can do my query to find the project_no from TABLE A that is not in the TABLE B? So, my result should say only one row found from TABLE A. This is very important. If there is no simplest way I can do such query then any other suggestions are welcome. Thanks. Ruchi.