Tom Lane wrote:
Food for thought: in 7.4,
regression=# select ('X '::char) = ('X'::char); ?column? ---------- t (1 row)
regression=# select ('Y '::char) = ('Y'::char); ?column? ---------- t (1 row)
regression=# select ('X '::char || 'Y '::char) = ('X'::char || 'Y'::char); ?column? ---------- t (1 row)
If we change || as is proposed in this thread, then the last case would yield 'false', because the first concatenation would yield 'X Y ' which is not equal to 'XY' no matter what you think about trailing spaces. I find it a bit disturbing that the concatenation of equal values would yield unequal values.
Well this indicates that the first two examples are questionable. 'X ' is quite-the-same as 'X', but not really-the-same.
CREATE OR REPLACE FUNCTION toms_name() RETURNS char(50)
as $BODY$
DECLARE fullname char(50);
DECLARE firstname char(50) := 'Tom';
DECLARE secondname char(50) := 'G';
DECLARE lastname char(50) := 'Lane';
BEGIN
fullname := firstname;
IF secondname != '' THEN
IF fullname != '' THEN
fullname := fullname || ' ';
END IF;
fullname := fullname || secondname;
END IF;
IF fullname != '' THEN
fullname := fullname || ' ';
END IF;
fullname := fullname || lastname;RETURN fullname; END; $BODY$ LANGUAGE 'plpgsql'
I find the result of this function quite surprising, and certainly not yielding what was intended (yes, this can avoided, I know). Surprise is getting bigger, if fullname is declared as text...
IMHO the bottom line here is that the SQL-spec behavior of type char(N)
is completely brain-dead.
Just for COBOL's sake, I suppose.
Regards, Andreas
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