Postgresql 下单

Question

I have a database where I need to retrieve the data as same order as it was populated in the table. The table name is bible When I type in table bible; in psql, it prints the data in the order it was populated with, but when I try to retrieve it, some rows are always out of order as in the below example:

table bible

-[ RECORD 1 ]-----------------------------------------------------------------------------------------------------------------------------------------
id      | 1
day     | 1
book    | Genesis
chapter | 1
verse   | 1
text    | In the beginning God created the heavens and the earth.
link    | https://api.biblia.com/v1/bible/content/asv.txt.txt?passage=Genesis1.1&key=dc5e2d416f46150bf6ceb21d884b644f
-[ RECORD 2 ]-----------------------------------------------------------------------------------------------------------------------------------------
id      | 2
day     | 1
book    | John
chapter | 1
verse   | 1
text    | In the beginning was the Word, and the Word was with God, and the Word was God.
link    | https://api.biblia.com/v1/bible/content/asv.txt.txt?passage=John1.1&key=dc5e2d416f46150bf6ceb21d884b644f
-[ RECORD 3 ]-----------------------------------------------------------------------------------------------------------------------------------------
id      | 3
day     | 1
book    | John
chapter | 1
verse   | 2
text    | The same was in the beginning with God.
link    | https://api.biblia.com/v1/bible/content/asv.txt.txt?passage=John1.2&key=dc5e2d416f46150bf6ceb21d884b644f

Everything is in order, but when I try to query the same thing using for example: select * from bible where day='1' or select * from bible where day='1' order by day or select * from bible where day='1' order by day, id; , I always get some rows out of order either in the day selected (here 1) or any other day. I have been using Django to interfere with Postgres database, but since I found this problem, I tried to query using SQL, but nothing, I still get rows out of order, although they all have unique ids which I verified with select count(distinct id), count(id) from bible;

- [ RECORD 1 ]------------------------------------------------------------------------------------------------------
id      | 1
day     | 1
book    | Genesis
chapter | 1
verse   | 1
text    | In the beginning God created the heavens and the earth.
link    | https://api.biblia.com/v1/bible/content/asv.txt.txt?passage=Genesis1.1&key=dc5e2d416f46150bf6ceb21d884b644f
-[ RECORD 2 ]-----------------------------------------------------------------------------------------------------------------------------------------
id      | 10
day     | 1
book    | Colossians
chapter | 1
verse   | 18
text    | And he is the head of the body, the church: who is the beginning, the firstborn from the dead; that in all things he might have the preemine
nce.
link    | https://api.biblia.com/v1/bible/content/asv.txt.txt?passage=Colossians1.18&key=dc5e2d416f46150bf6ceb21d884b644f
-[ RECORD 3 ]-----------------------------------------------------------------------------------------------------------------------------------------
id      | 11
day     | 1
book    | Genesis
chapter | 1
verse   | 2
text    | And the earth was waste and void; and darkness was upon the face of the deep: and the Spirit of God moved upon the face of the waters.
link    | https://api.biblia.com/v1/bible/content/asv.txt.txt?passage=Genesis1.2&key=dc5e2d416f46150bf6ceb21d884b644f

As you could see above if you notice, the ids are out of order 1, 10, 11.

my table

                              Table "public.bible";
Column  | Type | Collation | Nullable | Default | Storage  | Stats target | Description 
---------+------+-----------+----------+---------+----------+--------------+-------------
id      | text |           |          |         | extended |              | 
day     | text |           |          |         | extended |              | 
book    | text |           |          |         | extended |              | 
chapter | text |           |          |         | extended |              | 
verse   | text |           |          |         | extended |              | 
text    | text |           |          |         | extended |              | 
link    | text |           |          |         | extended |              | 
Access method: heap

The id field is of type text because I used pandas's to_sql() method to populate the bible table. I tried to drop the id column and then I added it again as a PK with ALTER TABLE bible ADD COLUMN id SERIAL PRIMARY KEY; but I still get data return out of order.

Is there anyway I can retrieve the data with ordering with id, without having some of the rows totally out of order? Thank you in advance!

Answer 1

Thou shalt cast thy id to integer to order it as number.

SELECT * FROM bible ORDER BY cast(id AS integer);

Answer 2

While @jordanvrtanoski is correct, the way to do this is django is:

>>> Bible.objects.extra(select={'id': 'CAST(id AS INTEGER)'}).order_by('id').values('id')
<QuerySet [{'id': 1}, {'id': 2}, {'id': 3}, {'id': 10}, {'id': 20}]>

Side note: If you want to filter on day as an example, you can do this:

>>> Bible.objects.extra(select={
    'id': 'CAST(id AS INTEGER)', 
    'day': 'CAST(day AS INTEGER)'}
).order_by('id').values('id', 'day').filter(day=2)
<QuerySet [{'id': 2, 'day': 2}, {'id': 10, 'day': 2}, {'id': 11, 'day': 2}, {'id': 20, 'day': 2}]>

Otherwise you get this issue: (notice 1 is followed by 10 and not 2 )

>>> Bible.objects.order_by('id').values('id')
<QuerySet [{'id': '1'}, {'id': '10'}, {'id': '2'}, {'id': '20'}, {'id': '3'}]>

I HIGHLY suggest you DO NOT do any of this, and set your tables correctly (have the correct column types and not have everything as text ), or your query performance is going to suck.. BIG TIME

Answer 3

Building on both answers of @jordanvrtanoski and @Javier Buzzi, and some search online, the issue is because the ids are of type TEXT (or VARCHAR too), so, you would need to cast the id to type INTEGER as in the following:

ALTER TABLE bible ALTER COLUMN id TYPE integer USING (id::integer);

Now here is my table

                                                Table "public.bible"
Column  |  Type   | Collation | Nullable |                 Default                 | Storage  | Stats target | Description 
---------+---------+-----------+----------+-----------------------------------------+----------+--------------+-------------
id      | integer |           |          | nextval('bible_id_seq'::regclass) | plain    |              | 
day     | text    |           |          |                                         | extended |              | 
book    | text    |           |          |                                         | extended |              | 
chapter | text    |           |          |                                         | extended |              | 
verse   | text    |           |          |                                         | extended |              | 
text    | text    |           |          |                                         | extended |              | 
link    | text    |           |          |                                         | extended |              | 
Indexes:
    "lesson_unique_id" UNIQUE CONSTRAINT, btree (id)
Referenced by:
    TABLE "notes_note" CONSTRAINT "notes_note_verse_id_5586a4bf_fk" FOREIGN KEY (verse_id) REFERENCES days_lesson(id) DEFERRABLE INITIALLY DEFERRED
Access method: heap

Hope this helps other people, and thank you everyone!