Postgresql sorting mixed alphanumeric data

问题

Running this query:

select name from folders order by name

returns these results:

alphanumeric
a test
test 20
test 19
test 1
test 10

But I expected:

a test
alphanumeric
test 1
test 10
test 19
test 20

What's wrong here?

回答1:

You can simply cast name column to bytea data type allowing collate-agnostic ordering:

SELECT name
FROM folders
ORDER BY name::bytea;

Result:

     name     
--------------
 a test
 alphanumeric
 test 1
 test 10
 test 19
 test 20
(6 rows)

回答2:

All of this methods sorted my selection in alphabetical order:

test 1
test 10
test 2
test 20

This solution worked for me (lc_collate: 'ru_RU.UTF8'):

SELECT name
FROM folders
ORDER BY SUBSTRING(name FROM '([0-9]+)')::BIGINT ASC, name;

test 1
test 2
test 10
test 20

回答3:

You may be able to manually sort by splitting the text up in case there is trailing numerals, like so:

SELECT * FROM sort_test
ORDER BY SUBSTRING(text FROM '^(.*?)( \\d+)?$'),
         COALESCE(SUBSTRING(text FROM ' (\\d+)$')::INTEGER, 0);

This will sort on column text, first by all characters optionally excluding an ending space followed by digits, then by those optional digits.

Worked well in my test.

Update fixed the string-only sorting with a simple coalesce (duh).

回答4:

OverZealous answer helped me but didn't work if the string in the database begun with numbers followed by additional characters.

The following worked for me:

SELECT name
FROM folders
ORDER BY
COALESCE(SUBSTRING(name FROM '^(\\d+)')::INTEGER, 99999999),
SUBSTRING(name FROM '^\\d* *(.*?)( \\d+)?$'),
COALESCE(SUBSTRING(name FROM ' (\\d+)$')::INTEGER, 0),
name;

So this one:

Extracts the first number in the string, or uses 99999999.
Extracts the string that follows the possible first number.
Extracts a trailing number, or uses 0.

回答5:

select * from "public"."directory" where "directoryId" = 17888 order by
COALESCE(SUBSTRING("name" FROM '^(\d+)')::INTEGER, 99999999),
SUBSTRING("name" FROM '[a-zA-z_-]+'),
COALESCE(SUBSTRING("name" FROM '(\d+)$')::INTEGER, 0),
"name";

NOTE: Escape the regex as you need, in some languages, you will have to add one more "\".

In my Postgres DB, name column contains following, when I use simple order by name query:

1
10
2
21
A
A1
A11
A5
B
B2
B22
B3
M 1
M 11
M 2

Result of Query, After I have modified it:

1
2
10
21
A
A1
A5
A11
B
B2
B3
B22
M 1
M 2
M 11

回答6:

Tor's last SQL worked for me. However if you are calling this code from php you need add extra slashes.

SELECT name
FROM folders
ORDER BY
COALESCE(SUBSTRING(name FROM '^(\\\\d+)')::INTEGER, 99999999),
SUBSTRING(name FROM '^\\\\d* *(.*?)( \\\\d+)?$'),
COALESCE(SUBSTRING(name FROM ' (\\\\d+)$')::INTEGER, 0),
name;

回答7:

A Vlk's answer above helped me a lot, but it sorted items only by the numeric part, which in my case came second. My data was like (desk 1, desk 2, desk 3 ...) a string part, a space and a numeric part. The syntax in A Vlk's answer returned the data sorted by the number, and at that it was the only answer from the above that did the trick. However when the string part was different, (eg desk 3, desk 4, table 1, desk 5...) table 1 would get first from desk 2. I fixed this using the syntax below:

    ...order by SUBSTRING(name,'\\w+'), SUBSTRINGname FROM '([0-9]+)')::BIGINT ASC;

来源：https://stackoverflow.com/questions/7018628/postgresql-sorting-mixed-alphanumeric-data

标签

postgresql

sorting

alphanumeric