Có thể thay thế HTML hoặc các thực thể ký tự khác bằng các ký tự tương ứng bằng cách sử dụng hàm. Đầu tiên tạo ra một bảng nhân vật thực thể:
create table character_entity(
name text primary key,
ch char(1) unique
);
insert into character_entity (ch, name) values
(E'\u00C6','AElig'),(E'\u00C1','Aacute'),(E'\u00C2','Acirc'),(E'\u00C0','Agrave'),(E'\u0391','Alpha'),(E'\u00C5','Aring'),(E'\u00C3','Atilde'),(E'\u00C4','Auml'),(E'\u0392','Beta'),(E'\u00C7','Ccedil'),
(E'\u03A7','Chi'),(E'\u2021','Dagger'),(E'\u0394','Delta'),(E'\u00D0','ETH'),(E'\u00C9','Eacute'),(E'\u00CA','Ecirc'),(E'\u00C8','Egrave'),(E'\u0395','Epsilon'),(E'\u0397','Eta'),(E'\u00CB','Euml'),
(E'\u0393','Gamma'),(E'\u00CD','Iacute'),(E'\u00CE','Icirc'),(E'\u00CC','Igrave'),(E'\u0399','Iota'),(E'\u00CF','Iuml'),(E'\u039A','Kappa'),(E'\u039B','Lambda'),(E'\u039C','Mu'),(E'\u00D1','Ntilde'),
(E'\u039D','Nu'),(E'\u0152','OElig'),(E'\u00D3','Oacute'),(E'\u00D4','Ocirc'),(E'\u00D2','Ograve'),(E'\u03A9','Omega'),(E'\u039F','Omicron'),(E'\u00D8','Oslash'),(E'\u00D5','Otilde'),(E'\u00D6','Ouml'),
(E'\u03A6','Phi'),(E'\u03A0','Pi'),(E'\u2033','Prime'),(E'\u03A8','Psi'),(E'\u03A1','Rho'),(E'\u0160','Scaron'),(E'\u03A3','Sigma'),(E'\u00DE','THORN'),(E'\u03A4','Tau'),(E'\u0398','Theta'),
(E'\u00DA','Uacute'),(E'\u00DB','Ucirc'),(E'\u00D9','Ugrave'),(E'\u03A5','Upsilon'),(E'\u00DC','Uuml'),(E'\u039E','Xi'),(E'\u00DD','Yacute'),(E'\u0178','Yuml'),(E'\u0396','Zeta'),(E'\u00E1','aacute'),
(E'\u00E2','acirc'),(E'\u00B4','acute'),(E'\u00E6','aelig'),(E'\u00E0','agrave'),(E'\u2135','alefsym'),(E'\u03B1','alpha'),(E'\u0026','amp'),(E'\u2227','and'),(E'\u2220','ang'),(E'\u00E5','aring'),
(E'\u2248','asymp'),(E'\u00E3','atilde'),(E'\u00E4','auml'),(E'\u201E','bdquo'),(E'\u03B2','beta'),(E'\u00A6','brvbar'),(E'\u2022','bull'),(E'\u2229','cap'),(E'\u00E7','ccedil'),(E'\u00B8','cedil'),
(E'\u00A2','cent'),(E'\u03C7','chi'),(E'\u02C6','circ'),(E'\u2663','clubs'),(E'\u2245','cong'),(E'\u00A9','copy'),(E'\u21B5','crarr'),(E'\u222A','cup'),(E'\u00A4','curren'),(E'\u21D3','dArr'),
(E'\u2020','dagger'),(E'\u2193','darr'),(E'\u00B0','deg'),(E'\u03B4','delta'),(E'\u2666','diams'),(E'\u00F7','divide'),(E'\u00E9','eacute'),(E'\u00EA','ecirc'),(E'\u00E8','egrave'),(E'\u2205','empty'),
(E'\u2003','emsp'),(E'\u2002','ensp'),(E'\u03B5','epsilon'),(E'\u2261','equiv'),(E'\u03B7','eta'),(E'\u00F0','eth'),(E'\u00EB','euml'),(E'\u20AC','euro'),(E'\u2203','exist'),(E'\u0192','fnof'),
(E'\u2200','forall'),(E'\u00BD','frac12'),(E'\u00BC','frac14'),(E'\u00BE','frac34'),(E'\u2044','frasl'),(E'\u03B3','gamma'),(E'\u2265','ge'),(E'\u003E','gt'),(E'\u21D4','hArr'),(E'\u2194','harr'),
(E'\u2665','hearts'),(E'\u2026','hellip'),(E'\u00ED','iacute'),(E'\u00EE','icirc'),(E'\u00A1','iexcl'),(E'\u00EC','igrave'),(E'\u2111','image'),(E'\u221E','infin'),(E'\u222B','int'),(E'\u03B9','iota'),
(E'\u00BF','iquest'),(E'\u2208','isin'),(E'\u00EF','iuml'),(E'\u03BA','kappa'),(E'\u21D0','lArr'),(E'\u03BB','lambda'),(E'\u2329','lang'),(E'\u00AB','laquo'),(E'\u2190','larr'),(E'\u2308','lceil'),
(E'\u201C','ldquo'),(E'\u2264','le'),(E'\u230A','lfloor'),(E'\u2217','lowast'),(E'\u25CA','loz'),(E'\u200E','lrm'),(E'\u2039','lsaquo'),(E'\u2018','lsquo'),(E'\u003C','lt'),(E'\u00AF','macr'),
(E'\u2014','mdash'),(E'\u00B5','micro'),(E'\u00B7','middot'),(E'\u2212','minus'),(E'\u03BC','mu'),(E'\u2207','nabla'),(E'\u00A0','nbsp'),(E'\u2013','ndash'),(E'\u2260','ne'),(E'\u220B','ni'),
(E'\u00AC','not'),(E'\u2209','notin'),(E'\u2284','nsub'),(E'\u00F1','ntilde'),(E'\u03BD','nu'),(E'\u00F3','oacute'),(E'\u00F4','ocirc'),(E'\u0153','oelig'),(E'\u00F2','ograve'),(E'\u203E','oline'),
(E'\u03C9','omega'),(E'\u03BF','omicron'),(E'\u2295','oplus'),(E'\u2228','or'),(E'\u00AA','ordf'),(E'\u00BA','ordm'),(E'\u00F8','oslash'),(E'\u00F5','otilde'),(E'\u2297','otimes'),(E'\u00F6','ouml'),
(E'\u00B6','para'),(E'\u2202','part'),(E'\u2030','permil'),(E'\u22A5','perp'),(E'\u03C6','phi'),(E'\u03C0','pi'),(E'\u03D6','piv'),(E'\u00B1','plusmn'),(E'\u00A3','pound'),(E'\u2032','prime'),
(E'\u220F','prod'),(E'\u221D','prop'),(E'\u03C8','psi'),(E'\u0022','quot'),(E'\u21D2','rArr'),(E'\u221A','radic'),(E'\u232A','rang'),(E'\u00BB','raquo'),(E'\u2192','rarr'),(E'\u2309','rceil'),
(E'\u201D','rdquo'),(E'\u211C','real'),(E'\u00AE','reg'),(E'\u230B','rfloor'),(E'\u03C1','rho'),(E'\u200F','rlm'),(E'\u203A','rsaquo'),(E'\u2019','rsquo'),(E'\u201A','sbquo'),(E'\u0161','scaron'),
(E'\u22C5','sdot'),(E'\u00A7','sect'),(E'\u00AD','shy'),(E'\u03C3','sigma'),(E'\u03C2','sigmaf'),(E'\u223C','sim'),(E'\u2660','spades'),(E'\u2282','sub'),(E'\u2286','sube'),(E'\u2211','sum'),
(E'\u2283','sup'),(E'\u00B9','sup1'),(E'\u00B2','sup2'),(E'\u00B3','sup3'),(E'\u2287','supe'),(E'\u00DF','szlig'),(E'\u03C4','tau'),(E'\u2234','there4'),(E'\u03B8','theta'),(E'\u03D1','thetasym'),
(E'\u2009','thinsp'),(E'\u00FE','thorn'),(E'\u02DC','tilde'),(E'\u00D7','times'),(E'\u2122','trade'),(E'\u21D1','uArr'),(E'\u00FA','uacute'),(E'\u2191','uarr'),(E'\u00FB','ucirc'),(E'\u00F9','ugrave'),
(E'\u00A8','uml'),(E'\u03D2','upsih'),(E'\u03C5','upsilon'),(E'\u00FC','uuml'),(E'\u2118','weierp'),(E'\u03BE','xi'),(E'\u00FD','yacute'),(E'\u00A5','yen'),(E'\u00FF','yuml'),(E'\u03B6','zeta'),
(E'\u200D','zwj'),(E'\u200C','zwnj')
;
Đây là chức năng:
create or replace function entity2char(t text)
returns text as $body$
declare
r record;
begin
for r in
select distinct ce.ch, ce.name
from
character_entity ce
inner join (
select name[1] "name"
from regexp_matches(t, '&([A-Za-z]+?);', 'g') r(name)
) s on ce.name = s.name
loop
t := replace(t, '&' || r.name || ';', r.ch);
end loop;
for r in
select distinct
hex[1] hex,
('x' || repeat('0', 8 - length(hex[1])) || hex[1])::bit(32)::int codepoint
from regexp_matches(t, '&#x([0-9a-f]{1,8}?);', 'gi') s(hex)
loop
t := regexp_replace(t, '&#x' || r.hex || ';', chr(r.codepoint), 'gi');
end loop;
for r in
select distinct
chr(codepoint[1]::int) ch,
codepoint[1] codepoint
from regexp_matches(t, '&#([0-9]{1,10}?);', 'g') s(codepoint)
loop
t := replace(t, '&#' || r.codepoint || ';', r.ch);
end loop;
return t;
end;
$body$
language plpgsql immutable;
Sử dụng nó như thế này:
select entity2char('HH■XXXÆYYY×ZZZ■UUU');
entity2char
--------------------
HH■XXXÆYYY×ZZZ■UUU
Nó chỉ hoạt động cho UTF-8.
Có thể, nhưng bạn đang cố gắng phân tích cú pháp 'HTML' bằng' RegExp'. Bạn ** PHẢI ** đọc câu trả lời cho câu hỏi này trước: http://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags –