[cs] 在 MariaDb 的 DDL 中是什么意思

Question

I have a DDL for a table

create table AIRPORT (
    AIRP_CODE varchar(10)[cs] not null,
    AIRP_NAME nvarchar(60)[cs] not null,
    GEOR_ID_LOCATED integer not null,
    PRCC_CONST integer,
    AIRP_TIME_ZONE char(5),
    AIRP_TRANSLATION mediumtext,
    LCOUNT integer default 0
);

I am trying to figure out what does [cs] mean in it. I think its for collation but I am not sure how it works. Table DDL isn't written by me and I can't figure it out.

Answer 1

In that position would be CHARACTER SET and/or COLLATION .

An "airport code" would best be CHARACTER SET ascii . Depending on whether you want to allow case folding, you could use COLLATION ascii_bin (disallow folding) or COLLATION ascii_ci (allow folding).

For the airport name, it would probably be best to use UTF-8 :

AIRP_NAME varchar(60) CHARACTER SET utf8mb4 COLLATION utf8mb4_unicode_520_ci not null

Note: NVARCHAR is a notation from non-MySQL vendors; for MySQL the sharset is important.

Perhaps you also want to specify a charset for AIRP_TRANSLATION ? Again, utf8mb4 is probably appropriate.

(I have never seen "[cs]"; my advice is aimed at what should be specified in that context.)

Answer 2

That SQL code is invalid, period.

You must be missing information. Wherever you got the code from, there's possibly some documentation that explains what it is and how to use it. If it was handed to you by some other person, he didn't consider sharing the information with you.

Judging from column names and types, I suspect the code comes from the README file of an airport database available for download, perhaps in CSV format, and it's just a recommended table structure you are meant to take as starting point and adapt to your own system. My educated guess about [cs] is that it's an annotation to imply that those fields are case sensitive, meaning that you application should use eg MAD and not mad .

In any case, having no further context it's impossible to tell.