PosqtgreSQL string comparison

I try to compare strings in PostgreSQL.

Here are queries that I execute:

select 'UK (z'>'Ukraine';

This one returns true;

Then I try following one:

select 'UK ('>'Ukraine';

This one returns false;

I think, that 开发者_如何学编程both of these should return false , and on another PostgreSQL server it behaves correctly. But main server is producing incorrect results in such operations. What am I doing wrong?

If you are in doubt try:

SHOW lc_collate;

This will show you the default collation.

Now you can specify collation at the column level or the query level. Since your question is at the query level, you can:

select 'UK (z'::text > 'Ukraine' COLLATE "C"; -- and
select 'UK (z'::text > 'Ukraine' COLLATE "ucs_basic"; -- both return false

What's actually happening the natural language collation orders ignore whitespace and non-alphanumeric characters, so the first is whether 'UKz' > 'Ukraine' which it is, and the second is whether 'UK' is greater than 'Ukraine' which it is not.