search
HomeDatabaseMysql Tutorial Oracle数据库9i、10g里列转行各种方法比较

把字符串1,2,3,4,5,以逗号分隔,输出为行,也就是12345随手写了一个,Oracle10G以上有表如下SQLselect*fromt;IDNAM..

把字符串 '1,2,3,4,5',以逗号分隔,输出为行,也就是

1
2
3
4
5

随手写了一个, Oracle 10G 以上
有表如下



        ID NAME
---------- --------
         1 0
         1 1
         1 5
         1 2
         1 8
         1 10
         2 9
         2 7
         2 8
         3 你好
         3 他好
         3 大家好

12 rows selected.

然后客户那反馈说数据库说9i的,报错说connect by不能使用子查询。
于是再稍做修改,在确定逗号不会超过99个的前提下,直接写个常量100,可以支持9i
 

后来想想这样也不好,于是建议建立一张特定的IOT表,保存10000个数字,一般够用了。
建立一张IOT,共10000行,同样支持9i

  • create table tnumber(ele,constraint pk_tnumber primary key(ele)) organization index as 
  • select rownum id from dual connect by rownum=10000; 
  • 然后不再需要常量100,即保证准确,又保证较好的性能

            ID NAME
    ---------- --------
             1 0
             1 1
             1 5
             1 2
             1 8
             1 10
             2 9
             2 7
             2 8
             3 你好
             3 他好
             3 大家好

    12 rows selected.

    下面测试一下性能:转换50万行试试,美国服务器,测试环境:DELL D630 用了4年半的旧笔记本,磁盘都是碎片
    SQL> insert into t select rownum+4,'1,2,3,4' from dual connect by rownum

    500000 rows created.

    SQL> commit;

    Commit complete.

    set timi on
    SQL> set timi on
    SQL> create table t500 nologging as
         with   vmaxnum as (
                select  ele
                from    tnumber
                where   ele      select id,
                decode(pos,0,substr(name,lagpos+1),substr(name,lagpos+1,pos-lagpos-1)) name
         from   (select id,name,ele,pos,nvl(lag(pos) over (partition by id order by ele),0) lagpos
                 from   (select id,name,ele,
                                instr(name,',',1,ele) pos
                         from   (select /*+ all_rows no_merge(v2) use_merge(t,v2) */
                                        t.id,t.name,v2.ele
                                 from   t,vmaxnum v2
                                 where  ele      order  by id,ele;

    Table created.

    Elapsed: 00:00:16.48

    耗时16秒,香港服务器,含建表的写盘时间

    SQL> select count(*) from t500;

      COUNT(*)
    ----------
       2000012

    当然还有别的写法,比如简单的可以这样

    或者10G以上用正则表达式也可以实现
    这个方法可能不是最高效的,但也还可以。
    这个SQL的性能和字符串含有的逗号的个数有关,逗号越多,也就是分隔项越多,性能越差。

    本文出自 “专注J2EE系列规范下的..” 博客,请务必保留此出处

    ,美国空间
    Statement
    The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
    什么是oracle asm什么是oracle asmApr 18, 2022 pm 04:16 PM

    oracle asm指的是“自动存储管理”,是一种卷管理器,可自动管理磁盘组并提供有效的数据冗余功能;它是做为单独的Oracle实例实施和部署。asm的优势:1、配置简单、可最大化推动数据库合并的存储资源利用;2、支持BIGFILE文件等。

    oracle怎么查询所有索引oracle怎么查询所有索引May 13, 2022 pm 05:23 PM

    方法:1、利用“select*from user_indexes where table_name=表名”语句查询表中索引;2、利用“select*from all_indexes where table_name=表名”语句查询所有索引。

    Oracle怎么查询端口号Oracle怎么查询端口号May 13, 2022 am 10:10 AM

    在Oracle中,可利用lsnrctl命令查询端口号,该命令是Oracle的监听命令;在启动、关闭或重启oracle监听器之前可使用该命令检查oracle监听器的状态,语法为“lsnrctl status”,结果PORT后的内容就是端口号。

    oracle全角怎么转半角oracle全角怎么转半角May 13, 2022 pm 03:21 PM

    在oracle中,可以利用“TO_SINGLE_BYTE(String)”将全角转换为半角;“TO_SINGLE_BYTE”函数可以将参数中所有多字节字符都替换为等价的单字节字符,只有当数据库字符集同时包含多字节和单字节字符的时候有效。

    oracle怎么删除sequenceoracle怎么删除sequenceMay 13, 2022 pm 03:35 PM

    在oracle中,可以利用“drop sequence sequence名”来删除sequence;sequence是自动增加数字序列的意思,也就是序列号,序列号自动增加不能重置,因此需要利用drop sequence语句来删除序列。

    oracle怎么查询数据类型oracle怎么查询数据类型May 13, 2022 pm 04:19 PM

    在oracle中,可以利用“select ... From all_tab_columns where table_name=upper('表名') AND owner=upper('数据库登录用户名');”语句查询数据库表的数据类型。

    oracle查询怎么不区分大小写oracle查询怎么不区分大小写May 10, 2022 pm 05:45 PM

    方法:1、利用“LOWER(字段值)”将字段转为小写,或者利用“UPPER(字段值)”将字段转为大写;2、利用“REGEXP_LIKE(字符串,正则表达式,'i')”,当参数设置为“i”时,说明进行匹配不区分大小写。

    Oracle怎么修改sessionOracle怎么修改sessionMay 13, 2022 pm 05:06 PM

    方法:1、利用“alter system set sessions=修改后的数值 scope=spfile”语句修改session参数;2、修改参数之后利用“shutdown immediate – startup”语句重启服务器即可生效。

    See all articles

    Hot AI Tools

    Undresser.AI Undress

    Undresser.AI Undress

    AI-powered app for creating realistic nude photos

    AI Clothes Remover

    AI Clothes Remover

    Online AI tool for removing clothes from photos.

    Undress AI Tool

    Undress AI Tool

    Undress images for free

    Clothoff.io

    Clothoff.io

    AI clothes remover

    AI Hentai Generator

    AI Hentai Generator

    Generate AI Hentai for free.

    Hot Article

    R.E.P.O. Energy Crystals Explained and What They Do (Yellow Crystal)
    2 weeks agoBy尊渡假赌尊渡假赌尊渡假赌
    Repo: How To Revive Teammates
    4 weeks agoBy尊渡假赌尊渡假赌尊渡假赌
    Hello Kitty Island Adventure: How To Get Giant Seeds
    4 weeks agoBy尊渡假赌尊渡假赌尊渡假赌

    Hot Tools

    Dreamweaver CS6

    Dreamweaver CS6

    Visual web development tools

    SecLists

    SecLists

    SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

    MantisBT

    MantisBT

    Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.

    mPDF

    mPDF

    mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),

    ZendStudio 13.5.1 Mac

    ZendStudio 13.5.1 Mac

    Powerful PHP integrated development environment