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如何在Oracle数据库中更新CLOB字段

作者：allway2

在Oracle数据库中,Blob和Clob分别是两种用来存储大数据的字段类型,下面这篇文章主要给大家介绍了关于如何在Oracle数据库中更新CLOB字段的相关资料,需要的朋友可以参考下

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：

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：

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,
              (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(ye.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)<>''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%'' 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+"''")}
      ${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字段内容请搜索脚本之家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脚本之家！

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