修改clob字段并插入新表|转|

发表于  2011 年 12 月 14 日  由  惜分飞

链接：http://www.xifenfei.com/2143.html

标题：修改clob字段并插入新表

作者：惜分飞©版权所有[文章允许转载,但必须以链接方式注明源地址,否则追究法律责任.]

最近开发有个需求，需要替换一张表的clob字段中的某些字符串，然后插入的一张新表中，我查询了一些资料，利用function结合匿名块模拟实现
0、数据库版本

SQL> select * from v$version;
 
BANNER
-----------------------------------------------------------------------
 
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
PL/SQL Release 11.2.0.1.0 - Production
CORE    11.2.0.1.0      Production
TNS for 32-bit Windows: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production

1、创建替换clob中字符串函数

create or replace function replaceClob_new (
srcClob IN CLOB,
replaceStr IN VARCHAR2,
replaceWith IN VARCHAR2
--newClob OUT CLOB
) RETURN CLOB
IS
 
vBuffer    VARCHAR2 (32767);
l_amount   BINARY_INTEGER := 32767;
l_pos      PLS_INTEGER := 1;
l_clob_len PLS_INTEGER;
newClob  CLOB;
 
BEGIN
   newClob  := EMPTY_CLOB;
  -- initalize the new clob
 dbms_lob.createtemporary(newClob,TRUE);
 l_clob_len := dbms_lob.getlength(srcClob);
 WHILE l_pos < l_clob_len
  LOOP
    dbms_lob.read(srcClob, l_amount, l_pos, vBuffer);
    IF vBuffer IS NOT NULL THEN
      -- replace the text
      vBuffer := replace(vBuffer, replaceStr, replaceWith);
      -- write it to the new clob
      dbms_lob.writeappend(newClob, LENGTH(vBuffer), vBuffer);
    END IF;
    l_pos := l_pos + l_amount;
  END LOOP;
  RETURN newclob;
 
 EXCEPTION
  WHEN OTHERS THEN
    RAISE;
END;

2、创建原表，并测试该函数

SQL> CREATE TABLE t_clob(ID NUMBER,clob_xff CLOB);
 
Table created
 
--手工通过plsql dev插入一些数据（大于4000）
 
SQL> select dbms_lob.getlength(clob_xff) from t_clob;
 
DBMS_LOB.GETLENGTH(CLOB_XFF)
----------------------------
                        4856
 
SQL> select dbms_lob.getlength(replaceClob_new(clob_xff,'function','1')) from t_clob;
 
DBMS_LOB.GETLENGTH(REPLACECLOB
------------------------------
                          4814
 
SQL> set long 50
SQL> select clob_xff from t_clob where id=1;
 
CLOB_XFF
--------------------------------------------------
create or replace function replaceClob_new (
srcCl
 
SQL> select replaceClob_new(clob_xff,'function','1')
  2  from t_clob where id=1;
 
REPLACECLOB_NEW(CLOB_XFF,'FUNCTION','1')
--------------------------------------------------
create or replace 1 replaceClob_new (
srcClob IN C

3、编写匿名块实现插入功能

DECLARE
  A_CLOB CLOB;
  R_CLOB CLOB;
  VSTRT  NUMBER(4);
BEGIN
--否则会在新表的clob字段头部会有空格
  VSTRT := 1;
  SELECT REPLACECLOB_NEW(CLOB_XFF, 'function', 'xifenfei')
    INTO R_CLOB
    FROM T_CLOB
   WHERE ID = 1;
  INSERT INTO T_CLOB_NEW
    (ID, CLOB_XFF)
  VALUES
    (1, EMPTY_CLOB())
  RETURNING CLOB_XFF INTO A_CLOB;
  DBMS_LOB.WRITE(A_CLOB, DBMS_LOB.GETLENGTH(R_CLOB), VSTRT, R_CLOB);
  COMMIT;
END;

4、测试匿名块功能

SQL> set long 50
SQL> select clob_xff from t_clob where id=1;
 
CLOB_XFF
--------------------------------------------------
create or replace function replaceClob_new (
srcCl
 
SQL> select clob_xff from t_clob_new where id=1;
 
CLOB_XFF
--------------------------------------------------
create or replace xifenfei replaceClob_new (
srcCl

参考:http://space.itpub.net/111631/viewspace-605827