如何在Oracle数据库中更新CLOB字段

2024-08-10 13:26 数据库作者： allway2

前言

在本文中，我们将介绍在Oracle数据库中更新CLOB字段的方法和注意事项。CLOB（Character Large Object）是一种数据类型，用于存储大量文本数据，最大长度为4GB。更新CLOB字段需要特殊的处理，下面将详细说明。

了解CLOB字段

在介绍更新CLOB字段之前，首先需要了解CLOB字段的特点。CLOB字段通常用于存储较长的文本数据，比如文章内容、日志记录等。在更新CLOB字段时，我们需要注意以下几点：

CLOB字段通常存储在一个表的一行中，因此更新CLOB字段实际上是更新了整个表的一行数据。
CLOB字段的数据类型是可变长的，因此在更新时，我们可以对CLOB字段进行部分更改而不影响整个字段。
CLOB字段的读写速度相对较慢，因为CLOB字段的数据通常要存储在独立的表空间中。

更新CLOB字段

在Oracle中更新CLOB字段有多种方法，下面将介绍两种常用的方法。

方法一：使用UPDATE语句

更新CLOB字段最简单的方法是使用UPDATE语句。下面是一个更新CLOB字段的示例：

UPDATE 表名
SET CLOB字段 = '新的CLOB内容'
WHERE 条件;

在这个示例中，我们使用UPDATE语句来更新表中的CLOB字段。我们可以将新的CLOB内容直接赋值给CLOB字段。同时，我们可以使用WHERE子句来指定要更新的行。

需要注意的是，如果CLOB字段的长度超过4000个字符，我们需要使用CLOB类型的字面量，而不是普通的字符类型。例如：

UPDATE 表名
SET CLOB字段 = TO_CLOB('超过4000个字符的CLOB内容')
WHERE 条件;

这样可以确保更新操作正常进行。

方法二：使用DBMS_LOB包

另一种更新CLOB字段的方法是使用DBMS_LOB包。DBMS_LOB是Oracle提供的针对LOB对象（包括CLOB和BLOB）的操作包。使用DBMS_LOB包可以更灵活地更新和操作CLOB字段。下面是一个使用DBMS_LOB包来更新CLOB字段的示例：

DECLARE
  lob_loc CLOB;
BEGIN
  SELECT CLOB字段 INTO lob_loc
  FROM 表名
  WHERE 条件
  FOR UPDATE;

  DBMS_LOB.WRITE(lob_loc, LENGTH('新的CLOB内容'), 1, '新的CLOB内容');

  COMMIT;
END;

在这个示例中，我们首先声明了一个LOB变量，然后使用SELECT语句将CLOB字段的值赋给LOB变量。接着，我们使用DBMS_LOB包的WRITE过程来更新CLOB字段的内容。最后，我们使用COMMIT语句提交事务。

注意事项

在更新CLOB字段时，需要注意以下几点：

在UPDATE语句中，如果CLOB字段的长度超过4000个字符，需要使用CLOB类型的字面量或者使用DBMS_LOB包来操作。
在使用DBMS_LOB包更新CLOB字段时，需要在事务中进行操作，并使用COMMIT语句提交事务。
更新CLOB字段可能会对数据库性能产生影响，特别是当CLOB字段包含大量数据时。因此，我们应该谨慎使用更新操作，并尽量避免频繁更新CLOB字段。
在更新CLOB字段时，应该确保代码的正确性并测试更新操作的性能。如果更新操作执行时间较长，可以考虑使用分批更新的方式来提高效率。

附：oracle纯SQL更新插入clob类型字段

句式:

declare
  bname clob := 'select * from (SELECTorder by ad_code';
begin
 update dsy_t_query set Q_TABLE = bname where q_id = 'DEBT_ZW_YE_ZJYT';
commit;
end;

例子(注意转换单引号):

--2021051717_wuyc_截止政府债务余额分资金用途汇总表_修改条件
declare
  bname clob := 'select * from (SELECT
AD.CODE AD_CODE,
max(LPAD(''   '',(AD.levelno-2)*2,'' '')|| AD.NAME) AD_NAME,
AD.ISLEAF,
SUM(ye_qm) ye_qm, 
   SUM(tl_ye) tl_ye,
   SUM(gl_ye) gl_ye, 
   SUM(gl_gsgl_ye) gl_gsgl_ye, 
   SUM(jc_ye) jc_ye, 
   SUM(szjs_ye) szjs_ye,
   SUM(szjs_gdjt_ye) szjs_gdjt_ye,
   SUM(szjs_dxgx_ye) szjs_dxgx_ye,
   SUM(tdcb_ye) tdcb_ye,
   SUM(bzxzf_ye) bzxzf_ye,
   SUM(bzxzf_phgz) bzxzf_phgz,
   SUM(st_hj_ye) st_hj_ye, 
   SUM(zqjs_ye) zqjs_ye,
   SUM(jy_amt) jy_amt,
   SUM(kx_ye) kx_ye, 
   SUM(wh_ye) wh_ye,
   SUM(ylws_ye) ylws_ye,
   SUM(shbz_ye) shbz_ye,
   SUM(lycb_ye) lycb_ye, 
   SUM(nlsl_ye) nlsl_ye,
   SUM(nlsl_ydfp_ye) nlsl_ydfp_ye,
   SUM(gk_ye) gk_ye,
   SUM(syjc_ye) syjc_ye,
   SUM(wlss_ye) wlss_ye,
   SUM(nyjc_ye) nyjc_ye,
   SUM(zrzh_ye) zrzh_ye,
   SUM(qtxm_ye) qtxm_ye,
   SUM(fzbxzc_ye) fzbxzc_ye,
   SUM(wzczq_ye) wzczq_ye
 FROM
DSY_V_ELE_AD AD
 left join
(
       SELECT YE.ad_code,
              YE.ye_qm ye_qm,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,2)= ''01'' then nvl(YE.ye_qm,0) else 0 end) as tl_ye,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,2)= ''02'' then nvl(YE.ye_qm,0) else 0 end) as gl_ye, 
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,4)= ''0201'' then nvl(YE.ye_qm,0) else 0 end) as gl_gsgl_ye,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,2)= ''03'' then nvl(YE.ye_qm,0) else 0 end) as jc_ye, 
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,2)= ''04'' then nvl(YE.ye_qm,0) else 0 end) as szjs_ye,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,4)= ''0401'' then nvl(YE.ye_qm,0) else 0 end) as szjs_gdjt_ye,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,4)= ''0405'' then nvl(YE.ye_qm,0) else 0 end) as szjs_dxgx_ye,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,2)= ''05'' then nvl(YE.ye_qm,0) else 0 end) as tdcb_ye,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,2)= ''06'' then nvl(YE.ye_qm,0) else 0 end) as bzxzf_ye,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,4)= ''0604'' then nvl(YE.ye_qm,0) else 0 end) as bzxzf_phgz,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,2)= ''07'' then nvl(YE.ye_qm,0) else 0 end) as st_hj_ye,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,2)= ''08'' then nvl(YE.ye_qm,0) else 0 end) as zqjs_ye,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,2)= ''09'' then nvl(YE.ye_qm,0) else 0 end) as jy_amt,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,2)= ''10'' then nvl(YE.ye_qm,0) else 0 end) as kx_ye, 
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,2)= ''11'' then nvl(YE.ye_qm,0) else 0 end) as wh_ye,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,2)= ''12'' then nvl(YE.ye_qm,0) else 0 end) as ylws_ye,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,2)= ''13'' then nvl(YE.ye_qm,0) else 0 end) as shbz_ye,
  编程客栈            (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,2)= ''14'' then nvl(YE.ye_qm,0) else 0 end) as lycb_ye, 
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,2)= ''15'' then nvl(YE.ye_qm,0) else 0 end) as nlsl_ye,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,2)= ''16'' then nvl(YE.ye_qm,0) else 0 end) as gk_ye,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,3)= ''817'' then nvl(YE.ye_qm,0) else 0 end) as syjc_ye,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,3)= ''818'' then nvl(YE.ye_qm,0) else 0 end) as wlss_ye,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,2)= ''19'' then nvl(YE.ye_qm,0) else 0 end) as nyjc_ye,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,2)= ''20'' then nvl(YE.ye_qm,0) else 0 end) as zrzh_ye,
              (case when YE.ZJYT_ID LIKE ''01%'' and substr(ye.zjyt_id,1,4)<>''0102'' AND substr(YE.XMFL_ID,0,8)= ''15010101'' then nvl(YE.ye_qm,0) else 0 end) as nlsl_ydfp_ye,
              (case when substr(yphpe.zjyt_id,1,4)=''0102'' or (ye.zjyt_id is not null  and substr(ye.zjyt_id,1,2)=''01'' and substr(ye.zjyt_id,1,4)<>http://www.devze.com''0102'' and (ye.xmfl_id is null or substr(YE.XMFL_ID,0,2)= ''99'')) then nvl(YE.ye_qm,0) else 0 end) as qtxm_ye,
              (CASE WHEN YE.ZJYT_ID LIKE ''02%python'' THEN nvl(YE.ye_qm,0) ELSE 0 END) as fzbxzc_ye,
               (CASE WHEN YE.ZJYT_ID is null THEN nvl(YE.ye_qm,0) ELSE 0 END) as wzczq_ye 
                FROM Debt_t_Fact_Zqzwye ye
                LEFT JOIN DSY_V_ELE_AG AG
          ON YE.AG_ID = AG.guid
         AND YE.ad_code = ag.PROVINCE
                where 1=1
              and  ye.pe_id = ''${peid}''
  ${if(zwlx_id=='''',""," and ye.zwlb_id like  ''"+zwlx_id+"%''")}
      ${if(zwlx=='''',""," and ye.zwlb_id like  ''"+zwlx+"%''")}
      ${if(dataType=='''',""," and ye.data_type= ''"+dataType+"''")}
      python${if(len(adid) == 0,""," and ye.ad_code in (''" + REPLACE(adid ,",","'',''") + "'')")}
) T
ON T.AD_CODE like AD.CODE||''%''
WHERE 1=1 ${if(len(adid) == 0," "," and AD.code in (''" + REPLACE(adid ,",","'',''") + "'')")}
group by AD.code,ad.name,AD.ISLEAF)
where abs(nvl(ye_qm,0)) <> 0
order by ad_code';
begin
 update dsy_t_query set Q_TABLE = bname where q_id = 'DEBT_ZW_YE_ZJYT';
commit;
end;

总结

本文介绍了在Oracle数据库中更新CLOB字段的方法和注意事项。我们可以使用UPDATE语句直接更新CLOB字段，也可以使用DBMS_LOB包进行更灵活的操作。在更新CLOB字段时，需要注意数据类型、事务和性能等方面的问题。

到此这篇关于如何在Oracle数据库中更新CLOB字段的文章就介绍到这了,更多相关Oracle更新CLOB字段内容请搜索编程客栈(www.devze.com)以前的文章或继续浏览下面的相关文章希望大家以后多多支持编程客栈(www.devze.com)！

继续阅读：oracle clob更新 oracle更新clob字段 oracle更新clob字段sql语句

如何在Oracle数据库中更新CLOB字段

目录

前言

了解CLOB字段

更新CLOB字段

方法一：使用UPDATE语句

方法二：使用DBMS_LOB包

注意事项

附：oracle纯SQL更新插入clob类型字段

总结

更多精彩内容

精彩评论

最新数据库

CentOS 9 Stream 上如何安装 SQL Server 2019

SQL Server导入Excel数据的简单图文教程

查看MySQL中已经创建的存储过程及其定义

详解SparkSql输出数据的方式

一文深入理解MySQL中的UTF-8与UTF-8MB4字符集

数据库排行榜

Hadoop Key Management Server (KMS)配置及测试

spark报错ERROR ObjectStore: Version information found in metastore differs 2.1.0 from expected schema version 1.2.0. Schema verififcation is disabled hive.metastore.schema.verification so setting version.

解决Navicat远程连接MySQL出现 10060 unknow error的方法

redis-cluster集群调优之cluster-require-full-coverage参数

Navicat连接Oracle数据库的详细步骤与注意事项