In SQL Query, How to Compare Across Different Rows

In SQL query, it is easy to compare values in different columns for same row. However, when compare value at column_A of Row 1 to the values at column_B of Rows 2 to 3, it would be hard. Sure, you always can write the cursor to process rows one by one. Here is a quick way: INNER JOIN this table by itself, you would get following rows: New row 1 = old row 1 and 1 New row 2 = old row 1 and 2 New row 3 = old row 1 and 3 New row 4 = old row 2 and 1 New row 5 = old row 2 and 2 New row 6 = old row 2 and 3 New row 7 = old row 3 and 1 New row 8 = old row 3 and 2 New row 9 = old row 3 and 3 Now you will be able to compare column_A and column_B at new rows 2 to 3, which is what you want. Just remember to eliminate row 1 and row 4 to 9.