PostgreSQL Sort

Question

I have a sort problem in PostgreSQL with below data:

name
-----
@CF
@CG
CD
CE

I used select name from table order by name, the

Answer 1

Just add that to the order by clause:

ORDER BY CASE WHEN LEFT(name,1) = '@' THEN 0 ELSE 1 END ASC, name ASC

Answer 2

Use this:

SELECT name
      FROM table 
     ORDER BY name WHEN LEFT(name, 1) = '@' 
                   THEN 0 ELSE 1 END, name

Answer 3

Your undisclosed collation setting obviously ignores the @ character for sort order. Either switch to another collation as suggested by @Craig. Or, if you want to stick to your collation for the rest of the string, add a special case for leading @.

In Postgres you can order by boolean values directly. Default order is FALSE, TRUE, NULL.

ORDER BY name !~~ '@%', name

!~~ being the Postgres shorthand for NOT LIKE.

Answer 4

Use PostgreSQL's collation support to tell it you want a particular collation.

Given:

CREATE TABLE t AS VALUES ('CD'),('CE'),('@CF'),('@CE');

You can force byte-wise collation using:

SELECT * FROM t ORDER BY column1 COLLATE "C";

The "C" collation is a byte-wise collation that ignores national language rules, encoding, etc.