Oracle RowNum Considerations

1. Use rownum you must include the first record, and if you do not include the first record, the result will not be returned. Because RowNum is a pseudo-column, it is a column that is added after the result set. And it was arranged starting from 1.

2, when using RowNum, only the East order by field is the primary key, the query results will be sorted before the calculation of rownum, conversely, if the sort field is not a primary key, there will be rownum, in the case of sorting the result set.

3, sorting paging is to note that Oracle's sorting results and optimization, if the sort field has more than one record, the same record may appear in multiple pages; The workaround is to sort by using the original sort field, in addition to the field that determines the unique field.

Oracle RowNum Considerations