问题
After a lot of reading and experimentation, it seems like I want PRIMARY strength for searching, but TERTIARY or IDENTICAL for ordering. Main question: Is that possible to achieve with H2 (or any other DB)?
Secondary question: Am I the only one here or would any of you also like the above combination? Some confirmation would be helpful for my sanity.
Background: It seems like the collation can only be set at the very beginning when creating the database. So I want to make sure to pick the right one. I am mainly thinking of these use cases (for now):
A search field where the user can start typing to filter a table: Here PRIMARY seems the most appropriate, in order to avoid missing any results (user is used to Google...). Although, it would be nice to be able to give the user the option to enable secondary or tertiary collation to do more precise searching.
Ordering: When the user clicks a table column to order the contents, TERTIARY/IDENTICAL ordering seems appropriate. That's what I am used to from everyday experience.
I read the offical H2 docs here: http://www.h2database.com/html/grammar.html#set_collation. and here: http://www.h2database.com/html/datatypes.html#varchar_ignorecase_type Some more related info: Collation STRENGTH and local language relation
The test sql (from https://groups.google.com/forum/?fromgroups=#!topic/h2-database/lBksrrcuGdY):
drop all objects;
set collation english STRENGTH PRIMARY;
create table test(name varchar);
insert into test values ('À'), ('Ä'), ('Â'), ('A'), ('à'), ('ä'), ('â'), ('a'), ('àa'), ('äa'), ('âa'), ('aa'), ('B'), ('b');
select * from test where name like 'a' order by name;
select * from test order by name;
回答1:
If you want to have two behaviours for a single data you have to:
- split data over two columns,
- or uses two operator sets.
For your purpose, it is common to store "canonical" representation of a raw data in order to search on canonical form and then sort/display raw data. May be you should use some "text search engine" such as Apache Lucene.
For pure H2 solutions, you can use H2 alias with Computed columns or with query criteria. First solution allows indexing to speed up your queries.
来源：https://stackoverflow.com/questions/13849244/h2-database-collation-strength-what-to-choose