oracle blob字段转为varchar2

 

注意 return clob 类型。

varchar2  在schema级和在PL/SQL代码级长度限制不同

4000 ，32767

 所以反回用 clob类型。

 

create or replace Function Blob_To_Varchar (Blob_In In Blob) Return clob
Is
    V_Varchar Varchar2(32767);
     V_Varchar1 Varchar2(32767);
    V_Start Pls_Integer := 1;
    V_Buffer Pls_Integer := 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;

    Return V_Varchar1;

End Blob_To_Varchar;

 

 

 

同类函数：

create or replace function get_blobvar(tempblob in Blob) return varchar2 is
  ret_buf       varchar2(32767);
  l_blob        BLOB;
  l_blob_length NUMBER;
  l_amount      BINARY_INTEGER := 10000; -- must be <= ~32765.
  l_offset      INTEGER := 1;
  l_buffer      RAW(20000);
  l_text_buffer VARCHAR2(32767);
  l_break_at    PLS_INTEGER := 250;

BEGIN
  l_blob := tempblob;
  IF (l_blob IS NULL ) THEN
    return '';
  end if;
  l_blob_length := DBMS_LOB.GETLENGTH(l_blob);
  ret_buf:='';
  --return to_char(l_blob_length);
  FOR i IN 1 .. CEIL(l_blob_length / l_amount) LOOP
    DBMS_LOB.READ(l_blob, l_amount, l_offset, l_buffer);
    l_text_buffer := UTL_RAW.CAST_TO_VARCHAR2(l_buffer);
    return l_text_buffer;
    FOR j IN 1 .. CEIL(LENGTH(l_text_buffer) / l_break_at) LOOP
     --ret_buf := SUBSTR(CONVERT(l_text_buffer, 'ZHS16GBK', 'AL16UTF16'),
     ret_buf := ret_buf || SUBSTR(l_text_buffer,
                        (((j - 1) * l_break_at) + 1),
                        LEAST(LENGTH(l_text_buffer) - ((j - 1) * l_break_at),
                              l_break_at));
    END LOOP;
    l_offset := l_offset + l_amount;
  END LOOP;
  return ret_buf;
EXCEPTION
  WHEN OTHERS THEN
    DBMS_OUTPUT.PUT_LINE('!ERROR: ' || SUBSTR(SQLERRM, 1, 247));
    RAISE;
 
END get_blobvar;

 

 

 转 clob

Create Or Replace Function Blob_To_Clob (Blob_In In Blob) Return Clob
Is
V_Clob Clob;
V_Varchar Varchar2(4000);
V_Start Pls_Integer := 1;
V_Buffer Pls_Integer := 4000;
G_Nls_Db_Char Varchar2(60);
Begin
Select Userenv('LANGUAGE') Into G_Nls_Db_Char From Dual;

If Dbms_Lob.Getlength(Blob_In) Is Null Then
         Return Empty_Clob(); 
End If;

Dbms_Output.Put_Line('TEST:' || Ceil(Dbms_Lob.Getlength(Blob_In)));

Dbms_Lob.Createtemporary(V_Clob, True);

For I In 1..Ceil(Dbms_Lob.Getlength(Blob_In) / V_Buffer) Loop

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'));

Dbms_Lob.Writeappend(V_Clob, Length(V_Varchar), V_Varchar);

V_Start := V_Start + V_Buffer;
End Loop;

--Dbms_Output.Put_Line(V_Varchar);

Return V_Clob;

End Blob_To_Clob;