问题
Is there a way with PostgreSQL to sort rows with NULL values in fields to the end of the selected table?
Like:
SELECT * FROM table ORDER BY somevalue, PUT_NULL_TO_END
回答1:
First of all, NULL values are sorted last in default ascending order. You don't have to do anything extra.
The issue applies to descending order, which is the perfect inverse and thus sorts NULL values first. The solution @Mosty pointed out was introduced with PostgreSQL 8.3:
ORDER BY somevalue DESC NULLS LAST
For PostgreSQL 8.2 and older or other RDBMS without this standard SQL feature you can substitute:
ORDER BY (somevalue IS NULL), somevalue DESC
FALSE sorts before TRUE, so NULL values come last, just like in the example above.
Related later answer:
- PostgreSQL sort by datetime asc, null first?
回答2:
Does this make the trick?
ORDER BY somevalue DESC NULLS LAST
Taken from: http://www.postgresql.org/docs/9.0/static/sql-select.html
来源：https://stackoverflow.com/questions/7621205/sort-null-values-to-the-end-of-a-table