通过关键词截取病历数据

```sql
CREATE OR REPLACE FUNCTION JH_SUBSTR_BY_KEY_SPP(BLOB_IN  IN BLOB,
                                                strStart in VARCHAR2,
                                                strEnd   in VARCHAR2)
  RETURN VARCHAR2 IS
  V_VARCHAR  VARCHAR2(32767);
  V_VARCHAR1 VARCHAR2(32767);
  V_START    PLS_INTEGER := 1;
  V_BUFFER   PLS_INTEGER := 30000;
  V_RETURN   VARCHAR2(4000);
BEGIN

IF DBMS_LOB.GETLENGTH(BLOB_IN) IS NULL THEN
    RETURN '';
  END IF;
  V_VARCHAR1 := '';
  --return to_char(Ceil(Dbms_Lob.Getlength(Blob_In) / V_Buffer));
  FOR I IN 1 .. CEIL(DBMS_LOB.GETLENGTH(BLOB_IN) / V_BUFFER) LOOP
    --当转换出来的字符串乱码时，可尝试用注释掉的函数
    --V_Varchar := Utl_Raw.Cast_To_Varchar2(Utl_Raw.Convert(Dbms_Lob.Substr(Blob_In, V_Buffer, V_Start),'SIMPLIFIED CHINESE_CHINA.ZHS16GBK', 'AMERICAN_THE NETHERLANDS.UTF8'));
    V_VARCHAR  := UTL_RAW.CAST_TO_VARCHAR2(DBMS_LOB.SUBSTR(BLOB_IN,
                                                           V_BUFFER,
                                                           V_START));
    V_VARCHAR1 := V_VARCHAR1 || V_VARCHAR;
  
    V_START := V_START + V_BUFFER;
  END LOOP;
  if (INSTR(V_VARCHAR1, strStart, 1, 1)) < 1 then
    return '';
  end if;
  if (INSTR(V_VARCHAR1, strEnd, 1, 1)) < 1 then
    return '';
  end if;
  if (INSTR(V_VARCHAR1, strEnd, 1, 1) - INSTR(V_VARCHAR1, strStart, 1, 1)) < 2000 then
    V_RETURN := substr(V_VARCHAR1,
                       INSTR(V_VARCHAR1, strStart, 1, 1) + length(strStart),
                       INSTR(V_VARCHAR1, strEnd, 1, 1) -
                       INSTR(V_VARCHAR1, strStart, 1, 1) - length(strStart));
  else
    V_RETURN := substr(V_VARCHAR1,
                       INSTR(V_VARCHAR1, strStart, 1, 1) + length(strStart),
                       2000);
  end if;

V_RETURN := ltrim(V_RETURN, '：');
  V_RETURN := ltrim(V_RETURN, ':');
  V_RETURN := ltrim(V_RETURN, '。');
  RETURN V_RETURN;

END JH_SUBSTR_BY_KEY_SPP;
```