oracle function 获取拼音首字母

CREATE OR REPLACE FUNCTION F_GET_PY_CAP(P_NAME IN VARCHAR2) RETURN VARCHAR2 AS
  V_WORD    VARCHAR2(10);
  V_COMPARE VARCHAR2(100);
  V_RETURN  VARCHAR2(4000);
  FUNCTION F_NLSSORT(P_WORD IN VARCHAR2) RETURN VARCHAR2 AS
  BEGIN
    RETURN NLSSORT(P_WORD, 'NLS_SORT=SCHINESE_PINYIN_M');
  END;
BEGIN
  FOR I IN 1 .. LENGTH(P_NAME) LOOP
    V_WORD    := SUBSTR(P_NAME, I, 1);
    V_COMPARE := F_NLSSORT(V_WORD);
    IF V_COMPARE >= F_NLSSORT('a') AND V_COMPARE <= F_NLSSORT('z') THEN
      V_RETURN := V_RETURN || V_WORD;
    ELSIF V_COMPARE >= F_NLSSORT('A') AND V_COMPARE <= F_NLSSORT('Z') THEN
      V_RETURN := V_RETURN || V_WORD;
    ELSIF V_COMPARE >= F_NLSSORT('0') AND V_COMPARE <= F_NLSSORT('9') THEN
      V_RETURN := V_RETURN || V_WORD;
    ELSIF V_COMPARE >= F_NLSSORT('吖') AND V_COMPARE <= F_NLSSORT('驁') THEN
      V_RETURN := V_RETURN || 'A';
    ELSIF V_COMPARE >= F_NLSSORT('八') AND V_COMPARE <= F_NLSSORT('簿') THEN
      V_RETURN := V_RETURN || 'B';
    ELSIF V_COMPARE >= F_NLSSORT('嚓') AND V_COMPARE <= F_NLSSORT('錯') THEN
      V_RETURN := V_RETURN || 'C';
    ELSIF V_COMPARE >= F_NLSSORT('咑') AND V_COMPARE <= F_NLSSORT('鵽') THEN
      V_RETURN := V_RETURN || 'D';
    ELSIF V_COMPARE >= F_NLSSORT('妸') AND V_COMPARE <= F_NLSSORT('樲') THEN
      V_RETURN := V_RETURN || 'E';
    ELSIF V_COMPARE >= F_NLSSORT('发') AND V_COMPARE <= F_NLSSORT('猤') THEN
      V_RETURN := V_RETURN || 'F';
    ELSIF V_COMPARE >= F_NLSSORT('旮') AND V_COMPARE <= F_NLSSORT('腂') THEN
      V_RETURN := V_RETURN || 'G';
    ELSIF V_COMPARE >= F_NLSSORT('妎') AND V_COMPARE <= F_NLSSORT('夻') THEN
      V_RETURN := V_RETURN || 'H';
    ELSIF V_COMPARE >= F_NLSSORT('丌') AND V_COMPARE <= F_NLSSORT('攈') THEN
      V_RETURN := V_RETURN || 'J';
    ELSIF V_COMPARE >= F_NLSSORT('咔') AND V_COMPARE <= F_NLSSORT('穒') THEN
      V_RETURN := V_RETURN || 'K';
    ELSIF V_COMPARE >= F_NLSSORT('垃') AND V_COMPARE <= F_NLSSORT('擽') THEN
      V_RETURN := V_RETURN || 'L';
    ELSIF V_COMPARE >= F_NLSSORT('嘸') AND V_COMPARE <= F_NLSSORT('椧') THEN
      V_RETURN := V_RETURN || 'M';
    ELSIF V_COMPARE >= F_NLSSORT('拏') AND V_COMPARE <= F_NLSSORT('瘧') THEN
      V_RETURN := V_RETURN || 'N';
    ELSIF V_COMPARE >= F_NLSSORT('筽') AND V_COMPARE <= F_NLSSORT('漚') THEN
      V_RETURN := V_RETURN || 'O';
    ELSIF V_COMPARE >= F_NLSSORT('妑') AND V_COMPARE <= F_NLSSORT('曝') THEN
      V_RETURN := V_RETURN || 'P';
    ELSIF V_COMPARE >= F_NLSSORT('七') AND V_COMPARE <= F_NLSSORT('裠') THEN
      V_RETURN := V_RETURN || 'Q';
    ELSIF V_COMPARE >= F_NLSSORT('亽') AND V_COMPARE <= F_NLSSORT('鶸') THEN
      V_RETURN := V_RETURN || 'R';
    ELSIF V_COMPARE >= F_NLSSORT('仨') AND V_COMPARE <= F_NLSSORT('蜶') THEN
      V_RETURN := V_RETURN || 'S';
    ELSIF V_COMPARE >= F_NLSSORT('侤') AND V_COMPARE <= F_NLSSORT('籜') THEN
      V_RETURN := V_RETURN || 'T';
    ELSIF V_COMPARE >= F_NLSSORT('屲') AND V_COMPARE <= F_NLSSORT('鶩') THEN
      V_RETURN := V_RETURN || 'W';
    ELSIF V_COMPARE >= F_NLSSORT('夕') AND V_COMPARE <= F_NLSSORT('鑂') THEN
      V_RETURN := V_RETURN || 'X';
    ELSIF V_COMPARE >= F_NLSSORT('丫') AND V_COMPARE <= F_NLSSORT('韻') THEN
      V_RETURN := V_RETURN || 'Y';
    ELSIF V_COMPARE >= F_NLSSORT('帀') AND V_COMPARE <= F_NLSSORT('咗') THEN
      V_RETURN := V_RETURN || 'Z';
    ELSE
      V_RETURN := V_RETURN || SUBSTR(P_NAME, I, 1);
    END IF;
  END LOOP;
  RETURN UPPER(V_RETURN);
END;