1 create or replace Function BlobToVarchar (Blob_In In Blob) Return clob
 2 Is
 3     V_Varchar Varchar2(32767);
 4      V_Varchar1 Varchar2(32767);
 5     V_Start Pls_Integer := 1;
 6     V_Buffer Pls_Integer := 4000;
 7 Begin
 

 8  
 9     If Dbms_Lob.Getlength(Blob_In) Is Null Then
10         Return ‘‘;
11     End If;
12     V_Varchar1 := ‘‘;
13  --return to_char(Ceil(Dbms_Lob.Getlength(Blob_In) / V_Buffer));
14     For I In 1..Ceil(Dbms_Lob.Getlength(Blob_In) / V_Buffer) Loop
15         --當轉換出來的字符串亂碼時，可嘗試用註釋掉的函數
16         --
 
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‘));
17         V_Varchar :=  Utl_Raw.Cast_To_Varchar2(Dbms_Lob.Substr(Blob_In, V_Buffer, V_Start));
18         V_Varchar1 := V_Varchar1 ||
 
 V_Varchar;
19     
20         V_Start := V_Start + V_Buffer;
21     End Loop;
22  
23     Return V_Varchar1;
24  
25 End Blob_To_Varchar;

1.首先執行上面的函數，返回的是個clob

update DR_RPT_REPORT_DATASOURCE
set data_sql = 
c2b(to_clob((select replace(Blob_To_Varchar(data_sql),‘XXX‘,‘XXX‘) from DR_RPT_REPORT_DATASOURCE where data_id 
=‘XXXX‘ ))) where data_id = ‘‘ ;

ORA-22835 緩沖區對於 CLOB 到 CHAR 轉換或 BLOB 到 RAW 轉換而言太小