POSTGRESQL获得汉字首字拼音函数(转)

CREATE FUNCTION func_chinese_spell(str VARCHAR(2000)) RETURNS VARCHAR(2000) AS $$
DECLARE
word NCHAR(1);
code VARCHAR(2000);
i INTEGER;
chnstr VARCHAR(2000);
BEGIN
code := '';
i := 1;
chnstr := str;
WHILE LENGTH(chnstr)>0 LOOP
word := SUBSTRING(str,i,1);
code := code || CASE WHEN (ASCII(word) BETWEEN 19968 AND 19968+20901) THEN
(
SELECT p FROM
(
SELECT 'A' as p,N'驁' as w
UNION ALL SELECT 'B',N'簿'
UNION ALL SELECT 'C',N'錯'
UNION ALL SELECT 'D',N'鵽'
UNION ALL SELECT 'E',N'樲'
UNION ALL SELECT 'F',N'鰒'
UNION ALL SELECT 'G',N'腂'
UNION ALL SELECT 'H',N'夻'
UNION ALL SELECT 'J',N'攈'
UNION ALL SELECT 'K',N'穒'
UNION ALL SELECT 'L',N'鱳'
UNION ALL SELECT 'M',N'旀'
UNION ALL SELECT 'N',N'桛'
UNION ALL SELECT 'O',N'漚'
UNION ALL SELECT 'P',N'曝'
UNION ALL SELECT 'Q',N'囕'
UNION ALL SELECT 'R',N'鶸'
UNION ALL SELECT 'S',N'蜶'
UNION ALL SELECT 'T',N'籜'
UNION ALL SELECT 'W',N'鶩'
UNION ALL SELECT 'X',N'鑂'
UNION ALL SELECT 'Y',N'韻'
UNION ALL SELECT 'Z',N'咗'
) T
WHERE w>=word ORDER BY p ASC LIMIT 1
)
ELSE word END;
i := i + 1;
chnstr := SUBSTRING(str,i,LENGTH(str)-i + 1);
END LOOP;

RETURN code;
END;
$$LANGUAGE plpgsql;