Re: [SQL] text -> char

Peter Stamfest <peter(dot)stamfest(at)eunet(dot)at> wrote a couple weeks ago:
> create view three as select CAST(substr(descr, 2, 4) as char(8)) as
> d from one;

That should work, and as of today it does work in current sources:

regression=# create view three as select CAST(substr(descr, 2, 4) as char(8))
regression-# as d from one;
CREATE 278003 1
regression=# \d three
View "three"
Attribute | Type | Modifier
-----------+---------+----------
d | char(8) |
View definition: SELECT (substr(one.descr, 2, 4))::char(8) AS d FROM one;

Releases before 7.0 had a tendency to just discard casts :-( in a lot
of corner cases, and this is one of 'em. I've cleaned up the cast
problems I know about, but there may be some left...

> The char() function works neither:
> create view four as select char(substr(descr, 2, 4)) as d from one;
> ERROR: parser: parse error at or near "substr"

That's not a bug. CHAR is an SQL reserved word for a type --- the
parser is expecting a type length indicator, like "char(8)", when it
sees CHAR(.

While there is a function named "char", you can only get at it by
double-quoting the name so it no longer looks like a keyword:

select "char"(substr(descr, 2, 4)) as d from one;

Also note that this converts to the internal single-byte char type,
which is presumably not what you wanted anyway.

regards, tom lane